JP7412272B2 - Block polyisocyanate composition, resin composition and resin film - Google Patents

Description

The present invention relates to a block polyisocyanate composition, a resin composition, and a resin film.

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 have excellent weather resistance, and the demand for them is on the rise. However, since polyurethane resin paints are generally two-component, their use is extremely inconvenient. That is, a typical polyurethane resin coating consists of two components, a polyol and a polyisocyanate, and it is necessary to store the polyol and polyisocyanate separately and mix them at the time of coating. Another problem is that once the two are mixed, the paint gels in a short time and becomes unusable. Because polyurethane resin paints have such problems, it is extremely difficult to use them for automatic painting in the field of line painting such as automobile painting or weak electric painting. Furthermore, since isocyanates easily react with water, they cannot be used in water-based paints such as electrodeposition paints. Furthermore, when a paint containing isocyanate is used, it is necessary to thoroughly clean the coating machine and coating tank at the end of the work, which significantly reduces work efficiency.

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

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

On the other hand, as low-temperature baking type block polyisocyanates, research has been conducted on block polyisocyanates using active methylene compounds such as acetoacetate and malonic acid diester. For example, Patent Documents 1 and 2 propose block polyisocyanate compositions that cure at 90°C.

JP2002-322238A Japanese Patent Application Publication No. 2006-335954

However, in recent years, from the viewpoint of protecting the global environment, there has been a strong demand for adaptation to plastics with low heat resistance, and a block polyisocyanate composition that cures at a temperature lower than 90° C. has been desired. Under such circumstances, polyhydric polyols with hydroxyl groups do not gel or excessively thicken during storage, have good curability at temperatures below 80°C, and have excellent hardness and hardness of coatings obtained by curing at temperatures below 80°C. A material with excellent strength is not yet known.

The present invention has been made in view of the above circumstances, and provides a resin composition with good storage stability, and a coating film with good curability at a low temperature of about 80°C. Provided are block polyisocyanate compositions having excellent hardness and strength, and resin compositions and resin films using the block polyisocyanate compositions.

That is, the present invention includes the following aspects.
(1) A blocked polyisocyanate derived from a polyisocyanate and a blocking agent containing a malonic acid ester having a tertiary alkyl group;
1. A block polyisocyanate composition comprising one or more metal chelates,
The polyisocyanate has an average number of isocyanate groups of 4.7 or more and 8 or less , has an isocyanurate group, and has an average hydroxyl group functionality and one or more diisocyanates selected from the group consisting of aliphatic diisocyanates and alicyclic diisocyanates. A polyisocyanate derived from a polyol having a base number of 2.9 or more and 8.0 or less ,
A block polyisocyanate composition, wherein the content of the metal chelate is 0.05 parts by mass or more and 7 parts by mass or less with respect to 100 parts by mass of the block polyisocyanate.
( 2 ) The block polyisocyanate composition according to (1) , wherein the metal chelate is a metal chelate selected from the group consisting of aluminum chelate and titanium chelate.
( 3 ) The block polyisocyanate composition according to (1) or (2) , wherein the metal chelate is aluminum tris(acetylacetonate).
( 4 ) The block polyisocyanate composition according to ( 3 ), further comprising acetylacetone.
( 5 ) The block polyisocyanate composition according to any one of (1) to ( 4 ), wherein the weight average molecular weight Mw of the block polyisocyanate composition is 3.0×10 ³ or more.
( 6 ) The block polyisocyanate composition according to any one of (1) to ( 5 ), wherein a part of the block polyisocyanate has a structural unit derived from a hydrophilic compound.
( 7 ) The block polyisocyanate composition according to ( 6 ), wherein the hydrophilic compound contains one or more compounds selected from the group consisting of nonionic compounds and anionic compounds.
( 8 ) The block polyisocyanate composition according to any one of (1) to ( 7 ), wherein the malonic acid ester having a tertiary alkyl group is di-tert-butyl malonate.
( 9 ) The blocked polyisocyanate composition according to any one of (1) to ( 8 ), wherein the blocking agent further contains a malonic acid ester having a secondary alkyl group.
( 10 ) The block polyisocyanate composition according to ( 9 ), wherein the malonic acid ester having a secondary alkyl group is diisopropyl malonate.
(1 1 ) A resin composition comprising the block polyisocyanate composition according to any one of (1) to (1 0 ) and a polyhydric hydroxy compound.
(1 2 ) The resin composition according to (1 1 ), wherein the polyhydric hydroxy compound has a glass transition temperature Tg of 0°C or more and 100°C or less.
(1 3 ) The resin composition according to (1 1 ) or (1 2 ), wherein the polyhydric hydroxy compound has a weight average molecular weight Mw of 5.0×10 ³ or more and 2.0×10 ⁵ or less.
(1 4 ) The resin composition according to any one of (1 1 ) to (1 3 ), wherein the polyhydric hydroxy compound has a hydroxyl value of 30 mgKOH/g or more and 250 mgKOH/g or less.
(1 5 ) In any one of (1 1 ) to (1 4 ), the content of the blocked polyisocyanate is 1 part by mass or more and 200 parts by mass or less with respect to 100 parts by mass of the polyhydric hydroxy compound. The resin composition described.
(1 6 ) A resin film obtained by curing the resin composition according to any one of (1 1 ) to (1 5 ).
( 17 ) Gel fraction when a resin film with a thickness of 40 μm obtained by heating and curing the resin composition at 80°C for 30 minutes was immersed in acetone for 24 hours at 23°C after being stored at 23°C for 1 week. is 83% by mass or more, the resin film according to (1 6 ).
(1 8 ) A resin film having a thickness of 40 μm obtained by heating and curing the resin composition on glass at 80° C. for 30 minutes has a Koenig hardness of 40 times or more at 23° C., (1 6 ) or ( 17 ).
(1 9 ) The maximum tensile stress at 23°C of a resin film having a thickness of 40 μm obtained by curing the resin composition by heating it at 80°C for 30 minutes is 12.0 MPa or more, (1 6 ) to (1 8) ).The resin film described in any one of ).

According to the block polyisocyanate composition of the above aspect, when it is made into a resin composition, it has good storage stability, and when it is made into a coating film, it has good curability, hardness and strength at a low temperature of about 80°C. An excellent block polyisocyanate composition can be provided. The resin composition of the above embodiment contains the block polyisocyanate composition, has good storage stability, and has excellent curability, hardness, and strength at a low temperature of about 80° C. when formed into a coating film. The resin film of the above embodiment is obtained by curing the resin composition, and has excellent curability, hardness, and strength at a low temperature of about 80°C.

Hereinafter, a mode for carrying out the present invention (hereinafter referred to as "this embodiment") will be described in detail. Note that the present invention is not limited to the following embodiment. The present invention can be implemented with appropriate modifications within the scope of its gist.

Note that in this specification, "polyol" means a compound having two or more hydroxy groups (-OH).
As used herein, "polyisocyanate" means a reaction product in which a plurality of monomer compounds having one or more isocyanate groups (-NCO) are bonded.

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

≪Blocked polyisocyanate composition≫
The blocked polyisocyanate composition of this embodiment includes a blocked polyisocyanate and one or more metal chelates.

The blocked polyisocyanate is derived from a polyisocyanate and a blocking agent containing a malonic acid ester having a tertiary alkyl group.

The polyisocyanate has an isocyanurate group and is derived from one or more diisocyanates selected from the group consisting of aliphatic diisocyanates and alicyclic diisocyanates.

The average number of isocyanate groups in the polyisocyanate is 3.5 or more, preferably 4.0 or more, more preferably 4.5 or more, and even more preferably 4.7 or more. When the average number of isocyanate groups of the polyisocyanate is at least the above lower limit, when formed into a coating film, it has excellent curability, hardness and strength at a low temperature of about 80°C. On the other hand, the upper limit of the average number of isocyanate groups in the polyisocyanate is not limited, and may be, for example, 20, 10, or 8.
The average number of isocyanate groups of the polyisocyanate can be determined, for example, from the number average molecular weight Mn of the polyisocyanate and the isocyanate group content (NCO content) using the following formula.

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

The number average molecular weight Mn of the polyisocyanate is, for example, the number average molecular weight based on polystyrene measured by GPC. Specifically, it can be measured using the method described in Examples below.

The isocyanate group content (NCO content) can be measured, for example, using the method shown below.
Accurately weigh 2 g or more and 3 g or less of polyisocyanate into a flask (Wg). Then, 20 mL of toluene is added to dissolve the polyisocyanate. Next, 20 mL of a 2N toluene solution of di-n-butylamine is added, and after mixing, the mixture is left at room temperature for 15 minutes. Then add 70 mL of isopropyl alcohol and mix. This solution is then titrated to an indicator with 1N hydrochloric acid solution (Factor F). The obtained titration value is defined as V2mL. Then, without polyisocyanate, the titration value obtained is taken as V1 ml. Next, the isocyanate group (NCO) content (% by mass) of the polyisocyanate is calculated from the following formula.

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

The content of the metal chelate is 0.05 parts by mass or more and 7 parts by mass or less, preferably 0.1 parts by mass or more and 6 parts by mass or less, and 0.15 parts by mass or more and 5.0 parts by mass or less, based on 100 parts by mass of the block polyisocyanate. It is more preferably 5 parts by mass or less, and even more preferably 0.2 parts by mass or more and 5 parts by mass or less. When the content of the metal chelate is equal to or higher than the above lower limit, a coating film tends to have excellent curability, hardness, and strength at a low temperature of about 80°C. On the other hand, when the content of the metal chelate is at most the above upper limit, the metal chelate can be prevented from remaining undissolved, and the storage stability of the resin composition can be improved.
The content of metal chelate can be calculated, for example, from the blending ratio of raw materials. Alternatively, the content of metal chelate can be determined by, for example, nuclear magnetic resonance (NMR), infrared absorption spectroscopy (IR), gas chromatography (GC), mass spectrometry (MS), or atomic absorption spectrometry (AAS). ), inductively coupled plasma (ICP) emission spectrometry, etc.

By using a malonic acid ester having a tertiary alkyl group as a blocking agent, the blocked polyisocyanate composition of this embodiment has good storage stability when made into a resin composition, and when made into a coating film. It is possible to achieve both the performance of excellent curability at a low temperature of about 80°C. Furthermore, by including a metal chelate, it is possible to improve the curability at a low temperature of about 80° C. when formed into a coating film, and the coating film has excellent hardness and strength.

Hereinafter, each component contained in the block polyisocyanate composition of this embodiment will be explained in detail.

<Block polyisocyanate>
Blocked polyisocyanate is a reaction product of polyisocyanate and a blocking agent. That is, in the blocked polyisocyanate, at least some of the isocyanate groups in the polyisocyanate are blocked with a blocking agent.

[Polyisocyanate]
The polyisocyanate used in the production of block polyisocyanate is a reaction product obtained by reacting multiple monomer compounds (hereinafter sometimes referred to as "isocyanate monomers") having one or more isocyanate groups (-NCO). It is.
The isocyanate monomer preferably has 4 or more and 30 or less carbon atoms. Specific examples of the isocyanate monomer include the following. These isocyanate monomers may be used alone or in combination of two or more.
(1) Aromatic diisocyanates such as diphenylmethane-4,4'-diisocyanate (MDI), 1,5-naphthalene diisocyanate, tolylene diisocyanate (TDI), xylylene diisocyanate, m-tetramethylxylylene diisocyanate (TMXDI).
(2) 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate (hereinafter sometimes referred to as "HDI"), 2,2,4-trimethyl-1,6-diisocyanatohexane, 2, Aliphatic diisocyanates such as 4,4-trimethyl-1,6-hexamethylene diisocyanate, 2-methylpentane-1,5-diisocyanate (MPDI), and lysine diisocyanate (hereinafter sometimes referred to as "LDI").
(3) Fats such as isophorone diisocyanate (hereinafter sometimes referred to as "IPDI"), 1,3-bis(diisocyanate methyl) cyclohexane, 4,4'-dicyclohexylmethane diisocyanate, diisocyanate norbornane, di(isocyanate methyl) norbornane, etc. Cyclic diisocyanates.
(4) 4-Isocyanate methyl-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.

The isocyanate monomer used in the production of polyisocyanate is one or more diisocyanates selected from the group consisting of aliphatic diisocyanates and alicyclic diisocyanates. Further, diisocyanate monomers other than the aliphatic diisocyanates and alicyclic diisocyanates mentioned above may be further used. Furthermore, as the isocyanate monomer, HDI or IPDI is more preferably used because of its industrial availability. Further, as the isocyanate monomer, HDI is more preferable from the viewpoint of reducing the viscosity of the block polyisocyanate component.

Furthermore, as the isocyanate monomer used in the production of polyisocyanate, either aliphatic diisocyanate or alicyclic diisocyanate may be used alone or in combination, but aliphatic diisocyanate and alicyclic diisocyanate may be used alone. It is preferable to use a combination of group diisocyanates, and it is particularly preferable to use HDI and IPDI. By using an aliphatic diisocyanate and an alicyclic diisocyanate, the toughness and hardness of the coating film can be further improved.

In the polyisocyanate, the mass ratio of the structural units derived from the aliphatic diisocyanate to the structural units derived from the alicyclic diisocyanate is preferably 50/50 or more and 95/5 or less, more preferably 60/40 or more and 92/8 or less, More preferably, the ratio is 65/35 or more and 90/10 or less.
When the mass ratio of the structural units derived from the aliphatic diisocyanate to the structural units derived from the alicyclic diisocyanate is at least the above lower limit, a decrease in flexibility when formed into a coating film is more effectively suppressed. can do. On the other hand, by being below the above upper limit, the hardness of the coating film can be further improved.
The mass ratio of the structural units derived from an aliphatic diisocyanate to the structural units derived from an alicyclic diisocyanate can be calculated, for example, using the following method. First, from the mass of unreacted diisocyanate after reaction and the concentration of aliphatic diisocyanate and alicyclic diisocyanate in this unreacted diisocyanate obtained by gas chromatography measurement, the mass of unreacted aliphatic diisocyanate and the concentration of unreacted alicyclic diisocyanate are determined. Calculate the mass of Next, the mass of the unreacted aliphatic diisocyanate and the mass of the unreacted alicyclic diisocyanate calculated above are subtracted from the mass of the charged aliphatic diisocyanate and the mass of the alicyclic diisocyanate, respectively, and the resulting difference is calculated as the aliphatic diisocyanate. The mass of the structural unit derived from the group diisocyanate and the mass of the structural unit derived from the alicyclic diisocyanate. Next, 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 is determined. The ratio is obtained.

The polyisocyanate has an isocyanurate group, and in addition to the isocyanurate group, one type selected from the group consisting of an allophanate group, a uretdione group, an iminooxadiazinedione group, an isocyanurate group, a urethane group, and a biuret group. It can have the above functional groups.

(polyol)
The polyisocyanate is preferably one derived from the above diisocyanate monomer and a polyol having an average number of hydroxyl functional groups of 2.9 or more and 8.0 or less. Thereby, the average number of isocyanate groups of the obtained polyisocyanate can be increased. In the polyisocyanate, a urethane group is formed by the reaction between the hydroxyl group of the polyol and the isocyanate group of the diisocyanate monomer.

The average number of hydroxyl functional groups of the polyol is preferably 2.9 or more and 8.0 or less, more preferably 3 or more and 6 or less, even more preferably 3 or more and 5 or less, and particularly preferably 3 or 4. In addition, the average number of hydroxyl functional groups of a polyol here is the number of hydroxyl groups present in one molecule of a polyol. The average number of hydroxyl functional groups of a polyol can be calculated using the following formula, for example. In addition, in the formula, "Mn" indicates the number average molecular weight of the polyol, "hydroxyl group content" indicates the content of hydroxyl groups (mass%) with respect to 100% by mass of the solid content of the polyol, and "17" indicates the molecular weight of the hydroxyl groups ( g/mol).

(Average number of hydroxyl functional groups in polyol) = {(Mn of polyol) x (hydroxyl group content) x 0.01}/17

The number average molecular weight of the polyol is preferably 100 or more and 1000 or less, 100 or more and 900 or less, more preferably 100 or more and 800 or less, even more preferably 100 or more and 700 or less, even more preferably 100 or more and 500 or less, and 100 or more and 400 or less. The following is even more preferable, and 100 or more and 350 or less are particularly preferable.
When the number average molecular weight of the polyol is within the above range, the block polyisocyanate composition has excellent low temperature curability when formed into a coating film, and also has excellent hardness and strength. The number average molecular weight Mn of the polyol is, for example, the number average molecular weight based on polystyrene measured by GPC.

Examples of such polyols include trimethylolpropane, glycerol, and polycaprolactone polyols derived from trivalent or higher polyhydric alcohols and ε-caprolactone.
Commercially available polycaprolactone polyols include, for example, Daicel's "Plaxel 303" (number average molecular weight 300), "Plaxel 305" (number average molecular weight 550), "Plaxel 308" (number average molecular weight 850), and "Plaxel 309". (number average molecular weight 900).

(Production method of polyisocyanate)
The method for producing polyisocyanate will be described in detail below.
Polyisocyanates can be produced by, for example, an allophanate reaction to form an allophanate group, a uretdione reaction to form a uretdione group, an iminooxadiazinedionation reaction to form an iminooxadiazinedione group, and an isocyanurate reaction to form an isocyanurate group. The reaction, the urethanization reaction to form a urethane group, and the biuretization reaction to form a biuret group are performed at once in the presence of an excess of isocyanate monomer, and after the reaction is completed, 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 together, and a group consisting of an allophanate group, a uretdione group, an iminooxadiazinedione group, an isocyanurate group, a urethane group, and a biuret group. It is a reactant having one or more types selected from the following.
Alternatively, the above reactions may be carried out separately and the polyisocyanates obtained respectively may be mixed in a specific ratio.
From the viewpoint of ease of production, it is preferable to perform the above reaction at once to obtain the polyisocyanate, and from the viewpoint of freely adjusting the molar ratio of each functional group, it is preferable to produce them separately and then mix them.

(1) Method for producing allophanate group-containing polyisocyanate Allophanate group-containing polyisocyanate is obtained by adding alcohol to an isocyanate monomer and using an allophanate reaction catalyst.
The alcohol used to form the allophanate group is preferably an alcohol 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 alone or in combination of two or more.
Examples of monoalcohols include methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, and the like.
Examples of the dialcohol include ethylene glycol, 1,3-butanediol, neopentyl glycol, and 2-ethylhexanediol.
Among these, monoalcohols are preferred as alcohols, and monoalcohols with a molecular weight of 200 or less are more preferred.

Examples of the allophanatization reaction catalyst include, but are not limited to, alkyl carboxylates such as tin, lead, zinc, bismuth, zirconium, and zirconyl.
Examples of tin alkyl carboxylates (organotin compounds) include tin 2-ethylhexanoate and dibutyltin dilaurate.
Examples of lead alkyl carboxylates (organic lead compounds) include lead 2-ethylhexanoate.
Examples of zinc alkyl carboxylates (organozinc compounds) include zinc 2-ethylhexanoate.
Examples of bismuth alkyl carboxylates include bismuth 2-ethylhexanoate.
Examples of the alkyl carboxylate of zirconium include zirconium 2-ethylhexanoate.
Examples of the alkyl carboxylate of zirconyl include zirconyl 2-ethylhexanoate. These catalysts can be used alone or in combination of two or more.
Further, the isocyanurate reaction catalyst described below can also be an allophanate reaction catalyst. When the allophanatization reaction is carried out using the isocyanurate reaction catalyst described below, an isocyanurate group-containing polyisocyanate (hereinafter sometimes referred to as "isocyanurate type polyisocyanate") is naturally produced.
Among these, it is preferable from the viewpoint of economical production to perform the allophanate-forming reaction and the isocyanurate-forming reaction using the isocyanurate-forming reaction catalyst described below as the allophanate-forming reaction catalyst.

The lower limit of the usage amount of the allophanatization reaction catalyst mentioned above is preferably 10 mass ppm, more preferably 20 mass ppm, and preferably 40 mass ppm, based on 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 used is preferably 1000 mass ppm, more preferably 800 mass ppm, and preferably 600 mass ppm, based on the mass of the charged isocyanate monomer. More preferably, it is particularly preferably 500 ppm by mass.
That is, the amount of the above-mentioned allophanatization 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, based on 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.

Further, the lower limit of the allophanatization reaction temperature is preferably 40°C, more preferably 60°C, even more preferably 80°C, and particularly preferably 100°C.
Further, 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, even more preferably 80°C or higher and 140°C or lower, and 100°C or higher. It is particularly preferable that the temperature is 140°C or less.
When the allophanatization reaction temperature is equal to or higher than 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, coloring of the polyisocyanate, etc. tends to be more effectively suppressed.

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

Many of the uretodionation reaction catalysts can also promote the isocyanuration reaction at the same time.
When using a uretodionation reaction catalyst, the uretodionation reaction can be stopped by adding a deactivator for the uretodionation reaction catalyst, such as phosphoric acid or methyl p-toluenesulfonate, when the desired yield is reached. preferable.
Further, when obtaining a polyisocyanate having a uretdione group by heating one or more diisocyanates selected from the group consisting of the above aliphatic diisocyanate and the above alicyclic diisocyanate without using a uretdione reaction catalyst, the heating temperature is , 120°C or higher is preferable, and 150°C or higher and 170°C or lower is more preferable. 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 iminooxadiazinedionation reaction catalyst is usually used.
Examples of the iminooxadiazinedionation catalyst include those shown in 1) or 2) below.
1) (Poly)hydrogen fluoride represented by the general formula M [F _n ] or the general formula M [F _n (HF) _m ] (where m and n represent the relationship m/n>0) M is an n-charged cation (mixture) or one or more radicals with a total of n valences.)
2) A compound represented by the general formula R ¹ -CR' ₂ -C(O)O- or the general formula R ² =CR'-C(O)O- and a quaternary ammonium cation or A compound consisting of a quaternary phosphonium cation.
(In the formula, R ¹ and R ² are each independently a linear, branched, or cyclic, saturated or unsaturated perfluoroalkyl group having 1 to 30 carbon atoms. (It is an alkyl group or aryl group having 1 to 20 carbon atoms that may independently contain a hydrogen atom or a hetero atom.)

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

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

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

When the iminooxadiazinedionation reaction reaches a desired content of iminooxadiazinedione groups, the iminooxadiazinedionation reaction can be stopped. The iminooxadiazinedionation reaction can be stopped, for example, by adding an acidic compound to the reaction solution. Examples of the acidic compound include phosphoric acid, acidic phosphoric acid ester, sulfuric acid, hydrochloric acid, and sulfonic acid compounds. This neutralizes the iminooxadiazinedionation reaction catalyst, or inactivates it by thermal decomposition, chemical decomposition, or the like. After stopping the reaction, perform filtration if necessary.

(4) Method for producing isocyanurate group-containing polyisocyanate Catalysts for deriving isocyanurate group-containing polyisocyanate from isocyanate monomers include commonly used isocyanurate reaction catalysts.

Although the isocyanurate reaction catalyst is not particularly limited, it is generally preferable to use a basic catalyst. Specific examples of the isocyanurate reaction catalyst include those shown below.
1) Tetraalkylammonium hydroxides such as tetramethylammonium, tetraethylammonium, and tetrabutylammonium, and acetates, propionates, octylates, caprates, myristates, and benzoates of the tetraalkylammoniums. weak organic acid salts such as
2) Hydroxide of aryltrialkylammonium such as benzyltrimethylammonium and trimethylphenylammonium, and acetate, propionate, octylate, caprate, myristate, benzoate, etc. of the aryltrialkylammonium. weak organic acid salts.
3) Hydroxides of hydroxyalkylammonium such as trimethylhydroxyethylammonium, trimethylhydroxypropylammonium, triethylhydroxyethylammonium, and triethylhydroxypropylammonium, and acetate, propionate, octylate, and capric acid of the hydroxyalkylammonium. weak organic acid salts such as salts, myristates, benzoates, etc.
4) Metal salts of tin, zinc, lead, etc. of alkyl carboxylic acids such as acetic acid, propionic acid, caproic acid, octylic acid, capric acid, myristic acid, etc.
5) Metal alcoholates such as sodium and potassium.
6) Aminosilyl group-containing compounds such as hexamethylene disilazane.
7) Mannich bases.
8) Mixtures of tertiary amines and epoxy compounds.
9) Phosphorous compounds such as tributylphosphine.

Among them, from the viewpoint of not producing unnecessary by-products, the isocyanurate reaction catalyst is preferably a quaternary ammonium hydroxide or a weak organic acid salt of quaternary ammonium, and tetraalkylammonium hydroxide, More preferably, it is an organic weak acid salt of tetraalkylammonium, a hydroxide of aryltrialkylammonium, or a weak organic acid salt of aryltrialkylammonium.

The upper limit of the usage amount of the above-mentioned isocyanurate reaction catalyst is preferably 1000 mass ppm, more preferably 500 mass ppm, and 100 mass ppm based on the mass of the charged isocyanate monomer. is even more preferable.
On the other hand, the lower limit of the usage amount of the isocyanurate reaction catalyst mentioned above is not particularly limited, but may be, for example, 10 mass ppm.

The isocyanurate reaction temperature is preferably 50°C or more and 120°C or less, more preferably 60°C or more and 90°C or less. When the isocyanurate reaction temperature is at most the above upper limit, coloring of the polyisocyanate, etc. tends to be more effectively suppressed.

When the desired conversion rate (the ratio of the mass of polyisocyanate produced in the isocyanurate reaction to the mass of the charged isocyanate monomer) is reached, the isocyanurate reaction is carried out using an acidic compound (for example, phosphoric acid, acidic phosphoric acid). ester, etc.).
In addition, in order to obtain 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 reaction at an early stage, and the reaction conditions, especially the amount and method of addition of the catalyst, must be carefully selected. be. For example, a method of adding the catalyst in portions at regular intervals is recommended as a suitable method.
Therefore, the conversion rate of the isocyanurate reaction for obtaining polyisocyanate is preferably 10% or more and 60% or less, more preferably 15% or more and 55% or less, and 20% or more and 50% or less. It is even more preferable.
When the conversion rate of the isocyanurate reaction is equal to or less than the above upper limit, the viscosity of the block polyisocyanate component can be lowered. Furthermore, when the conversion rate of the isocyanurate reaction is equal to or higher than the above lower limit, the reaction termination operation can be performed more easily.

Further, 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 above-mentioned isocyanate monomer.
Examples of alcohols having a valence of 1 or more and 6 or less that can be used include non-polymerizable alcohols and polymerizable alcohols. The term "non-polymerizable alcohol" as used herein means an alcohol that does not have a polymerizable group. On the other hand, "polymerizable alcohol" means an alcohol obtained by polymerizing a monomer having a polymerizable group and a hydroxyl group.
Examples of the non-polymerizable alcohol 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.
Examples of diols include 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 Examples include diols.
Examples of triols include glycerol, trimethylolpropane, and the like.
Examples of the tetraols include pentaerythritol and the like.

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

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

The polyether polyols are not particularly limited, but for example, alkylene oxides alone or in mixtures are added to polyhydric alcohols alone or in mixtures using alkali metal hydroxides or strong basic catalysts. Polyether polyols obtained by reacting alkylene oxide with a polyamine compound, and so-called polymer polyols obtained by polymerizing acrylamide or the like using the above-mentioned polyethers as a medium.
Examples of the alkali metal include lithium, sodium, potassium, and the like.
Examples of the strong basic catalyst include alcoholates, alkyl amines, and the like.
Examples of the polyhydric alcohol include those similar to those exemplified in the above polyester polyols.
Examples of the alkylene oxide include ethylene oxide, propylene oxide, butylene oxide, cyclohexene oxide, and styrene oxide.
Examples of the polyamine compound include ethylenediamines.

Acrylic polyols are not particularly limited, but include, for example, a monomer or a mixture of ethylenically unsaturated bond-containing monomers having a hydroxyl group, and other monomers containing ethylenically unsaturated bonds that can be copolymerized with this monomer. Or a mixture thereof may be copolymerized.
Examples of the ethylenically unsaturated bond-containing monomer having a hydroxyl group include, but are not limited to, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxy methacrylate. Examples include butyl.
Other ethylenically unsaturated bond-containing monomers that can be copolymerized with the ethylenically unsaturated bond-containing monomer having a hydroxyl group include, but are not particularly limited to, acrylic esters, methacrylic esters, unsaturated carboxylic acids, etc. , unsaturated amides, vinyl monomers, and vinyl 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 di-acrylate. - Ethylhexyl, lauryl acrylate, benzyl acrylate, phenyl acrylate, etc.
Examples of methacrylic acid esters include methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, and -2-methacrylate. - Ethylhexyl, lauryl methacrylate, benzyl methacrylate, phenyl methacrylate, etc.
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 the vinyl monomer include glycidyl methacrylate, styrene, vinyltoluene, vinyl acetate, acrylonitrile, and dibutyl fumarate.
Examples of the vinyl monomer having a hydrolyzable silyl group include vinyltrimethoxysilane, vinylmethyldimethoxysilane, and γ-(meth)acryloxypropyltrimethoxysilane.

Examples of the polyolefin polyols include hydroxyl-terminated polybutadiene and hydrogenated products thereof.

(5) Method for producing urethane group-containing polyisocyanate When a polyisocyanate containing a urethane group is derived from an isocyanate monomer, for example, an excess of the isocyanate monomer, the above polyol, and optionally an alcohol other than the above polyol, It can be produced by mixing and adding a urethanization reaction catalyst as needed.
Examples of the polyol include those exemplified in the above "polyol".
Examples of the alcohol include those exemplified in the above "method for producing isocyanurate group-containing polyisocyanate", excluding those exemplified in the above "polyol".
The urethanization reaction catalyst is not particularly limited, and examples thereof include tin-based compounds, zinc-based compounds, amine-based compounds, and the like.
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, coloring of the polyisocyanate, etc. tends to be more effectively suppressed.
Further, the urethanization reaction time is preferably 30 minutes or more and 4 hours or less, more preferably 1 hour or more and 3 hours or less, and even more preferably 1 hour or more and 2 hours or less.
The ratio of the molar amount of isocyanate groups in the isocyanate monomer to the molar amount of hydroxyl groups in the polyol (and alcohol other than the polyol, if necessary) is preferably 2/1 or more and 50/1 or less. When the molar ratio is equal to or higher than the lower limit, the viscosity of the polyisocyanate can be lowered. When the molar ratio is at most the above upper limit, the yield of the urethane group-containing polyisocyanate can be further increased.

(6) Method for producing biuret group-containing polyisocyanate Biuret-forming agents for inducing biuret group-containing polyisocyanate from isocyanate monomers are not particularly limited, but include, for example, water, monovalent 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 biuret forming agent. If the molar amount of isocyanate groups per mole of biuret forming agent is at least the above lower limit, the polyisocyanate will have a sufficiently low viscosity, and if it is below the above upper limit, the low temperature curability of the resin film will be further improved. do.

Further, a solvent may be used during the biuret formation reaction. The solvent may be any solvent as long as it dissolves the isocyanate monomer and the biuret forming agent such as water and forms a homogeneous phase under the reaction conditions.
Specific examples of the solvent include ethylene glycol solvents, phosphoric acid solvents, and the like.
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 the phosphoric acid solvent include trimethyl phosphate, triethyl phosphate, tripropyl phosphate, and tributyl phosphate.
These solvents may be used alone or in combination of two or more.
Among these, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol diacetate, or diethylene glycol dimethyl ether is preferred as the ethylene glycol solvent.
Further, as the phosphoric acid solvent, trimethyl phosphate or triethyl phosphate is preferable.

The biuret-forming reaction temperature is preferably 70°C or more and 200°C or less, more preferably 90°C or more and 180°C or less. When it is below the above upper limit, it tends to be possible to more effectively prevent coloring of the polyisocyanate.

The above-mentioned allophanatization reaction, uretodionation reaction, iminooxadiazinedionation reaction, isocyanurate reaction, urethanization reaction, and biuretation reaction may be performed sequentially, or some of them may be performed in parallel. Good too.
After the reaction is completed, unreacted isocyanate monomers are removed from the reaction solution by thin film distillation, extraction, etc. to obtain polyisocyanate.

Furthermore, 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 the antioxidant include hindered phenols such as 2,6-di-tert-butyl-p-cresol. Examples of the ultraviolet absorber include benzotriazole and benzophenone. These antioxidants and ultraviolet 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 based on the mass of the polyisocyanate.

[Blocking agent]
The blocking agent includes a malonic acid ester having a tertiary alkyl group. The blocking agent may contain one type of malonic acid ester having a tertiary alkyl group, or may contain two or more types.

Examples of malonic acid esters having a tertiary alkyl group include di-tert-butyl malonate, di-tert-pentyl malonate, and tert-butylethyl malonate. Among these, di-tert-butyl malonate is preferred.

(Malonic acid ester having a secondary alkyl group)
It is preferable that the blocking agent further contains a malonic acid ester having a secondary alkyl group. The blocking agent may contain one type of malonic acid ester having a secondary alkyl group, or may contain two or more types.

Examples of malonic acid esters having a secondary alkyl group include di-sec-butyl malonate, diisopropyl malonate, isopropylethyl malonate, and the like. Among these, diisopropyl malonate is preferred as the malonic acid ester having a secondary alkyl group.

Among these, the blocking agent preferably contains diisopropyl malonate as a malonic ester having a secondary alkyl group, and di-tert-butyl malonate as a malonic ester having a tertiary alkyl group.

(Other blocking agents)
In addition to malonic acid esters having a secondary alkyl group and malonic acid esters having a tertiary alkyl group, the blocking agents used in the production of blocked polyisocyanates have storage stability when made into a resin composition and when made into a resin film. The composition may further contain other blocking agents within a range that does not inhibit the low-temperature curability of the composition.
In addition, the content of the malonic acid ester having a secondary alkyl group and the malonic acid ester having a tertiary alkyl group is 50 mol% or more with respect to the total molar amount of all blocking agents used in the production of the blocked polyisocyanate. It is preferably at least 70 mol%, even more preferably at least 90 mol%, particularly preferably at least 95 mol%, and most preferably at least 100 mol%.
When the content of the malonic ester having a secondary alkyl group and the malonic ester having a tertiary alkyl group is within the above range, the low temperature curability of the resin film can be further improved.

Other blocking agents include, for example, 1) alcohol compounds, 2) alkylphenol compounds, 3) phenol compounds, and 4) malonic esters other than malonic esters having a secondary alkyl group and malonic esters having a tertiary alkyl group. Active methylene compounds, 5) Mercaptan compounds, 6) Acid amide compounds, 7) Acid imide compounds, 8) Imidazole compounds, 9) Urea compounds, 10) Oxime compounds, 11) Amine compounds, 12 ) imide compounds, 13) bisulfites, 14) pyrazole compounds, and 15) triazole compounds. More 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-ethocacyethanol, and 2-butoxyethanol.
2) Alkylphenol 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, 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, etc.
4) Active methylene compounds: dimethyl malonate, diethyl malonate, methyl acetoacetate, ethyl acetoacetate, acetylacetone, etc.
5) Mercaptan compounds: butyl mercaptan, dodecyl mercaptan, etc.
6) Acid amide compounds: acetanilide, acetate amide, ε-caprolactam, δ-valerolactam, γ-butyrolactam, etc.
7) Acid imide compounds: succinimide, maleic imide, etc.
8) Imidazole compounds: imidazole, 2-methylimidazole, etc.
9) Urea compounds: urea, thiourea, ethylene urea, etc.
10) Oxime compounds: formaldoxime, acetaldoxime, acetoxime, methyl ethyl ketoxime, cyclohexanone oxime, etc.
11) Amine compounds: diphenylamine, aniline, carbazole, di-n-propylamine, diisopropylamine, isopropylethylamine, etc.
12) Imine compounds: ethyleneimine, polyethyleneimine, etc.
13) Bisulfite compounds: sodium bisulfite, etc.
14) Pyrazole compounds: pyrazole, 3-methylpyrazole, 3,5-dimethylpyrazole, etc.
15) Triazole compounds: 3,5-dimethyl-1,2,4-triazole, etc.

[Hydrophilic compound]
At least a portion of the blocked polyisocyanate may have a structural unit derived from a hydrophilic compound, that is, a hydrophilic group.

A hydrophilic compound is a compound having a hydrophilic group. In addition to the hydrophilic group, the hydrophilic compound preferably has one or more active hydrogen groups per molecule of the hydrophilic compound for reacting with at least one isocyanate group of the polyisocyanate. Specific examples of the active hydrogen group include a hydroxyl group, a mercapto group, a carboxylic acid group, an amino group, and a thiol group.

Examples of the hydrophilic compound include nonionic compounds, cationic compounds, and anionic compounds. These hydrophilic compounds may be used alone or in combination of two or more. Among these, as the hydrophilic compound, nonionic compounds are preferred from the viewpoint of easy availability and resistance to electrical interaction with the compound, and anionic compounds are preferred from the viewpoint of suppressing a decrease in the hardness of the resulting resin film. Compounds are preferred.

(Nonionic compound)
Specific examples of nonionic compounds include monoalcohols and compounds in which ethylene oxide is added to the hydroxyl group of alcohol. Examples of monoalcohols include methanol, ethanol, butanol, and the like. Examples of compounds in which ethylene oxide is added to the hydroxyl group of alcohol include ethylene glycol, diethylene glycol, and polyethylene glycol. These nonionic compounds also have active hydrogen groups that react with isocyanate groups.
Among these, as the nonionic compound, polyethylene glycol monoalkyl ether, which is obtained by adding ethylene oxide to the hydroxyl group of a monoalcohol, is preferable because the water dispersibility of the block polyisocyanate composition can be improved with a small amount used.

The number of ethylene oxide added to the compound to which ethylene oxide is added is preferably 4 or more and 30 or less, more preferably 4 or more and 25 or less. When the number of ethylene oxides added is at least the above lower limit, water dispersibility tends to be more effectively imparted to the block polyisocyanate composition, and when the number of ethylene oxides added is at most the above upper limit, Precipitates of the block polyisocyanate composition tend to be less likely to occur during low-temperature storage.

The lower limit of the amount of nonionic hydrophilic groups added to the block polyisocyanate (hereinafter sometimes referred to as "content of nonionic hydrophilic groups") is determined from the viewpoint of water dispersion stability of the block polyisocyanate composition. Based on the solid content of the hydrophilic polyisocyanate composition, preferably 0.1% by mass, more preferably 0.15% by mass, even more preferably 0.20% by mass, particularly 0.25% by mass. preferable.
In addition, from the viewpoint of water resistance of the resulting resin film, the upper limit of the content of nonionic hydrophilic groups is preferably 55% by mass, and 50% by mass, based on the mass of the solid content of the block polyisocyanate composition. It is more preferably 48% by mass, even more preferably 44% by mass.
That is, the content of the nonionic hydrophilic group is preferably 0.1% by mass or more and 55% by mass or less, and 0.15% by mass or more and 50% by mass or less, based on the mass of the solid content of the block polyisocyanate composition. It is more preferably 0.20% by mass or more and 48% by mass or less, and particularly preferably 0.25% by mass or more and 44% by mass or less.
When the content of the nonionic hydrophilic group is within the above range, the block polyisocyanate composition is more likely to be dispersed in water and a homogeneous film is likely to be obtained.

When expressed in molar ratio, the amount of nonionic hydrophilic groups added to the block polyisocyanate is preferably 0.05 mol% or more and 8 mol% or less, and 0.10 mol% or less, based on 100 mol% of isocyanate groups of the raw material polyisocyanate. More preferably mol% or more and 5 mol% or less, further preferably 0.15 mol% or more and 4 mol% or less, particularly preferably 0.15 mol% or more and 3 mol% or less, and 0.15 mol% or more and 2 mol% or less. Most preferred.

(cationic compound)
Specific examples of the cationic compound include compounds having both a cationic hydrophilic group and an active hydrogen group. Further, 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 to form 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. From the viewpoint of ease of production, compounds having both a cationic hydrophilic group and an active hydrogen group are preferred.

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

The cationic compound and the alicyclic polyisocyanate can be reacted in the presence of a solvent. The solvent in this case is preferably one that does not contain active hydrogen groups, and specific examples thereof include ethyl acetate, propylene glycol monomethyl ether acetate, dipropylene glycol dimethyl ether, and the like.

The cationic hydrophilic group added to the blocked polyisocyanate is 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, and a sulfuric acid group.
Specific examples of the compound having a carboxyl group include formic acid, acetic acid, propionic acid, butyric acid, and lactic acid.
Specific examples of the compound having a sulfonic acid group include ethanesulfonic acid.
Specific examples of the compound having a phosphoric acid group include phosphoric acid, acidic phosphoric acid ester, and the like.
Specific examples of the compound having a halogen group include hydrochloric acid and the like.
Specific examples of the compound having a sulfate group include sulfuric acid and the like.
Among these, as the compound having an anionic group, a compound having a carboxy group is preferable, and acetic acid, propionic acid, or butyric acid is more preferable.

(Anionic compound)
Specific examples of the anionic hydrophilic group include a carboxy group, a sulfonic acid group, a phosphoric acid group, a halogen group, and a sulfuric acid group.
Specific examples of the anionic compound include compounds that have both an anionic group and an active hydrogen group, and more specifically, examples include compounds that have both an anionic group and an active hydrogen group. Examples include compounds having the group as a group.
Examples of monohydroxycarboxylic acids include 1-hydroxyacetic acid, 3-hydroxypropanoic acid, 12-hydroxy-9-octadecanoic acid, hydroxypivalic acid (hydroxypivalic acid), and lactic acid.
Examples of compounds having a carboxy group of polyhydroxycarboxylic acid as an anionic group include dimethylol acetic acid, 2,2-dimethylolbutyric acid, 2,2-dimethylolpentanoic acid, dihydroxysuccinic acid, dimethylolpropionic acid, etc. .
Further, compounds having both a sulfonic acid group and an active hydrogen group may also be mentioned, and more specifically, for example, isethionic acid and the like may be mentioned.
Among these, hydroxypivalic acid or dimethylolpropionic acid is preferable as the compound having both an anionic group and an active hydrogen group.

The anionic hydrophilic group added to the blocked polyisocyanate is preferably neutralized with an amine compound that is a basic substance.
Specific examples of the amine compound include ammonia, water-soluble amino compounds, and the like.
Specific examples of water-soluble amino compounds include monoethanolamine, ethylamine, dimethylamine, diethylamine, triethylamine, propylamine, dipropylamine, isopropylamine, diisopropylamine, triethanolamine, butylamine, dibutylamine, 2- Examples include ethylhexylamine, ethylenediamine, propylenediamine, methylethanolamine, dimethylethanolamine, diethylethanolamine, and morpholine. Further, tertiary amines such as triethylamine and dimethylethanolamine are also mentioned, and these can also be used. These amine compounds may be used alone or in combination of two or more.

<Metal chelate>
The metal chelate is not particularly limited, and examples thereof include chelates of one or more metals selected from the group consisting of boron (B), aluminum (Al), titanium (Ti), and zinc (Zr).
Among these, the metal chelate is preferably one or more selected from the group consisting of aluminum chelate and titanium chelate.
Examples of the aluminum chelate include diisopropoxyaluminum (ethylacetoacetate) aluminum tris (ethylacetoacetate), aluminum tris (acetylacetonate), and the like.
Examples of titanium chelates include diisopropoxy (acetylacetonate) titanium, diisopropoxy (ethylacetoacetate) titanium, tetraacetylacetonate titanium, titanium-1,3-propanedioxybis(ethylacetoacetate), and the like. Can be mentioned.
These metal chelates may be used alone or in combination of two or more.
Among these, aluminum tris (acetylacetonate) is preferable as the metal chelate. Moreover, when the block polyisocyanate composition of this embodiment contains aluminum tris (acetylacetonate) as a metal chelate, it is preferable that it further contains acetylacetone.

<Other components>
In addition to the block polyisocyanate and the metal chelate, the block polyisocyanate composition of the present embodiment can further contain additives such as a solvent.

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

<Method for producing block polyisocyanate composition>
The blocked polyisocyanate composition is not particularly limited, but can be produced, for example, by reacting the polyisocyanate with the blocking agent to obtain a blocked polyisocyanate, and then mixing the mixture with a metal chelate.

The blocking reaction between the polyisocyanate and the blocking agent can be carried out regardless of the presence or absence of a solvent, and a blocked polyisocyanate is obtained.
As the blocking agent, one kind of malonic acid ester having a tertiary alkyl group may be used, or two or more kinds thereof may be used in combination. Moreover, when using a malonic acid ester having a secondary alkyl group and a malonic acid ester having a tertiary alkyl group, one type of each may be used, or two or more types may be used in combination.
The amount of the blocking agent added may generally be 80 mol% or more and 200 mol% or less, and preferably 90 mol% or more and 150 mol% or less, based on the total molar amount of isocyanate groups.

In addition, in the blocking agent to be added, when a malonic acid ester having a secondary alkyl group and a malonic acid ester having a tertiary alkyl group are used, The molar ratio of malonic acid ester (malonic acid ester having a secondary alkyl/malonic acid ester having a tertiary alkyl) is more than 5/95 and less than 95/5, preferably 7/93 or more and 93/7 or less, and 10 /90 or more and 93/7 or less are more preferable, 20/80 or more and 93/7 or less are even more preferable, and 30/70 or more and 93/7 or less are particularly preferable. When the molar ratio is at least the lower limit above, the storage stability of the resin composition can be improved, and when the molar ratio is at most the upper limit above, the resin film can be cured at low temperatures. can be made good.

Furthermore, when a solvent is used, a solvent that is inert to isocyanate groups may be used.
When using a solvent, the content of non-volatile components based on 100 parts by mass of the block polyisocyanate composition may usually be 10 parts by mass or more and 95 parts by mass or less, preferably 20 parts by mass or more and 80 parts by mass or less. , more preferably 30 parts by mass or more and 75 parts by mass or less.

In the blocking reaction, organic metal salts such as tin, zinc, and lead, tertiary amine compounds, and alcoholates of alkali metals such as sodium may be used as catalysts.
The amount of the catalyst added varies depending on the temperature of the blocking reaction, etc., but is usually 0.05 parts by mass or more and 1.5 parts by mass or less, and 0.1 parts by mass based on 100 parts by mass of the polyisocyanate. The content is preferably 1.0 parts by mass or less.

The blocking reaction can generally be carried out at -20°C or higher and 150°C or lower, preferably at 0°C or higher and 100°C or lower, and more preferably at 10°C or higher and 80°C or lower. When the temperature of the blocking reaction is equal to or higher than the above lower limit, the reaction rate can be further increased, and when the temperature is equal to or lower than the above upper limit, side reactions can be further suppressed.
After the blocking reaction, neutralization treatment may be performed by adding an acidic compound or the like.
As the acidic compound, an inorganic acid or an organic acid may be used. Examples of the inorganic acid include hydrochloric acid, phosphorous acid, and phosphoric acid. Examples of the organic acid include methanesulfonic acid, p-toluenesulfonic acid, dioctyl phthalate, dibutyl phthalate, and the like.

After the blocking reaction, the metal chelate is mixed.
The blending amount of the metal chelate is 0.05 parts by mass or more and 7 parts by mass or less, preferably 0.1 parts by mass or more and 6 parts by mass or less, and 0.15 parts by mass, based on 100 parts by mass of the block polyisocyanate. It is more preferably 5.5 parts by mass or less, and even more preferably 0.2 parts by mass or more and 5 parts by mass or less. When the blending amount of the metal chelate is at least the above lower limit, the coating film tends to have excellent curability, hardness, and strength at a low temperature of about 80°C. On the other hand, when the amount of the metal chelate is at most the above upper limit, the metal chelate can be prevented from remaining undissolved, and the storage stability of the resin composition can be improved.

Moreover, when using a hydrophilic compound, it is obtained by making the said polyisocyanate, the said blocking agent, and the said hydrophilic compound react.

The reaction between the polyisocyanate and the hydrophilic compound and the reaction between the polyisocyanate and the blocking agent can be performed simultaneously, or after any reaction has been performed in advance, the second and subsequent reactions can be performed. Among these, the polyisocyanate and the hydrophilic compound are first reacted to obtain a hydrophilic compound-modified polyisocyanate modified with the hydrophilic compound, and then the obtained hydrophilic compound-modified polyisocyanate is reacted with a blocking agent. It is preferable to do so.

For the reaction between the polyisocyanate and the hydrophilic compound, an organic metal salt, a tertiary amine compound, or an alkali metal alcoholate may be used as a catalyst. Examples of the metal constituting the organic metal salt include tin, zinc, and lead. Examples of the alkali metal include sodium.

The reaction temperature between the polyisocyanate and the hydrophilic compound is preferably -20°C or more and 150°C or less, more preferably 30°C or more and 130°C or less. When the reaction temperature is equal to or higher than the above lower limit, the reactivity tends to be higher. Furthermore, when the reaction temperature is below the above upper limit, side reactions tend to be suppressed more effectively.

It is preferable to completely react the hydrophilic compound with the polyisocyanate so that the hydrophilic compound does not remain unreacted. By not remaining in an unreacted state, it tends to more effectively suppress the deterioration of the water dispersion stability of the block polyisocyanate composition and the low-temperature curability when formed into a resin film.

For the reaction between the hydrophilic compound-modified polyisocyanate and the blocking agent, the method described above as the blocking reaction can be used.

<Characteristics of block polyisocyanate composition>
[Weight average molecular weight Mw]
The weight average molecular weight Mw of the block polyisocyanate composition of the present embodiment is preferably 3.0×10 ³ or more, more preferably 3.0×10 ³ or more and 2.0×10 ⁵ or less, and 4.0×10 ³ or more. More preferably, it is 1.5×10 ⁵ or less. When the weight average molecular weight Mw is within the above range, the viscosity of the block polyisocyanate composition can be maintained better. The weight average molecular weight Mw can be measured, for example, by GPC.

≪Resin composition≫
The resin composition of this embodiment contains the above-mentioned block polyisocyanate composition and a polyhydric hydroxy compound. The resin composition of this embodiment can also be called a one-component resin composition containing a curing agent component and a base component.

The resin composition of this embodiment has good storage stability, and when formed into a coating film, it has excellent curability, hardness, and strength at a low temperature of about 80°C.
The constituent components of the resin composition of this embodiment will be explained in detail below.

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

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

[Polyether polyols]
Examples of the polyether polyols include those obtained using any of the methods (1) to (3) below.
(1) Polyether polyols or polytetramethylene glycols obtained by adding alkylene oxide alone or as a mixture to polyhydric alcohol alone or as a mixture.
(2) Polyether polyols obtained by reacting alkylene oxide with a polyfunctional compound.
(3) So-called polymer polyols obtained by polymerizing acrylamide or the like using the polyether polyols obtained in (1) or (2) as a medium.
Examples of the polyhydric alcohol include glycerol and propylene glycol.
Examples of the alkylene oxide include ethylene oxide and propylene oxide.
Examples of the polyfunctional compound include ethylenediamine and ethanolamines.

[Polyester polyols]
Examples of the polyester polyols include the following polyester polyols (1) or (2).
(1) Polyester polyol resins obtained by a condensation reaction of a dibasic acid alone or a mixture of two or more types and a polyhydric alcohol alone or a mixture of two or more types.
(2) Polycaprolactones obtained by ring-opening polymerization of ε-caprolactone with a polyhydric alcohol.
Examples of the dibasic acid include carboxylic acids such as succinic acid, adipic acid, dimer acid, maleic anhydride, phthalic anhydride, isophthalic acid, terephthalic acid, and 1,4-cyclohexanedicarboxylic acid.
Examples of the polyhydric alcohol include ethylene glycol, propylene glycol, diethylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, trimethylpentanediol, cyclohexanediol, trimethylolpropane, glycerol, and pentaerythritol. , 2-methylolpropanediol, ethoxylated trimethylolpropane, and the like.

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

[Fluorine-containing polyols]
Examples of the fluorine-containing polyols include fluoroolefins, cyclohexyl vinyl ethers, and hydroxyl which are disclosed in Reference 1 (Japanese Unexamined Patent Publication No. 57-34107), Reference 2 (Japanese Unexamined Patent Publication No. 61-275311), etc. Examples include copolymers of alkyl vinyl ethers and monocarboxylic acid vinyl esters.

[Acrylic polyols]
The acrylic polyols are, for example, polymerized with a polymerizable monomer having one or more active hydrogens in one molecule, or with a polymerizable monomer having one or more active hydrogens in one molecule, if necessary. , can be obtained by copolymerizing the polymerizable monomer and another copolymerizable monomer.

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

Examples of other monomers copolymerizable with the polymerizable monomer include those shown in (i) to (v) below. These may be used alone or in combination of two or more.
(i) Acrylic acid esters such as methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate.
(ii) Methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, lauryl methacrylate, glycidyl methacrylate, etc. .
(iii) Unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, itaconic acid.
(iv) Unsaturated amides such as acrylamide, N-methylolacrylamide, diacetone acrylamide and the like.
(v) Styrene, vinyltoluene, vinyl acetate, acrylonitrile, etc.

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

Specifically, the polymerizable UV-stable monomer includes, for example, 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine, 4-(meth)acryloylamino-2,2,6 , 6-tetramethylpiperidine, 1-crotonoyl-4-crotonoyloxy-2,2,6,6-tetramethylpiperidine, 2-hydroxy-4-(3-methacryloxy-2-hydroxypropoxy)benzophenone, etc. It will be done.

For example, an acrylic polyol can be obtained by solution polymerizing the above monomer components in the presence of a known radical polymerization initiator such as a peroxide or an azo compound, and diluting with an organic solvent as necessary. Can be done.

When obtaining a water-based acrylic polyol, it can be produced by a known method such as a method in which an olefinically unsaturated compound is solution-polymerized and converted into an aqueous layer, or emulsion polymerization. In that case, water solubility or water dispersibility can be imparted by neutralizing the acidic moiety of a carboxylic acid-containing monomer such as acrylic acid or methacrylic acid or a sulfonic acid-containing monomer with an amine or ammonia.

[Hydroxyl value and acid value of polyvalent hydroxy compound]
The hydroxyl value of the polyvalent hydroxy compound contained in the resin composition of the present embodiment is preferably 5 mgKOH/g or more and 300 mgKOH/g or less, more preferably 10 mgKOH/g or more and 280 mgKOH/g or less, and 30 mgKOH/g or more and 250 mgKOH/g or more. /g or less is more preferable. When the hydroxyl value of the polyhydric hydroxy compound is within the above range, a resin film having better various physical properties such as tensile strength can be obtained. The hydroxyl value of the polyhydric hydroxy compound can be measured, for example, using the method described in the Examples below. can do.

[Glass transition temperature Tg of polyvalent hydroxy compound]
The glass transition temperature Tg of the polyvalent hydroxy compound contained in the resin composition of the present embodiment is preferably 0°C or more and 100°C or less, more preferably 0°C or more and 90°C or less, and 0°C or more and 80°C or less. is more preferable, and particularly preferably 5°C or more and 70°C or less. When the glass transition temperature of the polyhydric hydroxy compound is within the above range, a resin film with better tensile strength can be obtained. The glass transition temperature of a polyhydric hydroxy compound can be measured, for example, using the method described in Examples below.

[Weight average molecular weight Mw of polyvalent hydroxy compound]
The weight average molecular weight Mw of the polyhydric hydroxy compound is preferably 5.0×10 ³ or more and 2.0×10 ⁵ or less, more preferably 5.0×10 ³ or more and 1.5×10 ⁵ or less. It is preferably 5.0×10 ³ or more and 1.0×10 ⁵ or less. When the hydroxyl value of the polyhydric hydroxy compound is within the above range, a resin film having better various physical properties such as tensile strength can be obtained. The weight average molecular weight Mw of the polyhydric hydroxy compound can be measured, for example, using the method described in the Examples below.

[NCO/OH]
The molar equivalent ratio (NCO/OH) of the isocyanate groups of the blocked polyisocyanate composition to the hydroxyl groups of the polyhydric hydroxy compound contained in the resin composition of the present embodiment is determined depending on the physical properties of the required resin film, but is usually , 0.01 or more and 22.5 or less.

[Content of block polyisocyanate composition]
In the resin composition of the present embodiment, the content of the blocked polyisocyanate may be such that the molar equivalent ratio of the isocyanate groups of the blocked polyisocyanate to the hydroxyl groups of the polyvalent hydroxy compound falls within the above range. It is preferably 1 part by mass or more and 200 parts by mass or less, more preferably 5 parts by mass or more and 200 parts by mass or less, even more preferably 6 parts by mass or more and 180 parts by mass or less, based on 100 parts by mass of the hydroxy compound. Particularly preferably 10 parts by mass or more and 150 parts by mass or less. When the content of the blocked polyisocyanate is within the above range, a resin film having better various physical properties such as tensile strength can be obtained. The content of blocked polyisocyanate can be calculated, for example, from the blending amount, or it can be identified and quantified using nuclear magnetic resonance (NMR) and gas chromatography/mass spectrometry (GC/MS). It can also be calculated using

<Other additives>
The resin composition of this embodiment may further contain other additives.
Examples of other additives include curing agents, curing catalysts, solvents, pigments (extender pigments, coloring pigments, metallic pigments, etc.), ultraviolet absorbers, and light stabilizers that can react with the crosslinkable functional group in the polyhydric hydroxy compound. agents, radical stabilizers, anti-yellowing agents that suppress discoloration during the baking process, coating surface conditioners, fluidity conditioners, pigment dispersants, antifoaming agents, thickeners, film-forming aids, and the like.

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

The curing catalyst may be a basic compound or a Lewis acidic compound.
Examples of the basic compound include metal hydroxide, metal alkoxide, metal carboxylate, metal acetylacetinate, onium salt hydroxide, onium carboxylate, onium salt halide, metal salt of active methylene compound, Examples include onium salts of active methylene compounds, aminosilanes, amines, and phosphines. The onium salt is preferably an ammonium salt, a phosphonium salt, or a sulfonium salt.
Examples of the Lewis acidic compound include organic tin compounds, organic zinc compounds, organic titanium compounds, and organic zirconium compounds.

Examples of the solvent include the same solvents as those exemplified in the block polyisocyanate composition.

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

<Method for manufacturing resin composition>
The resin composition of this embodiment can be used in both solvent-based and aqueous-based systems.

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

When producing a solvent-based resin composition, first, a curing agent and a curing catalyst that can react with the crosslinkable functional group in the polyhydric hydroxy compound are added to the polyhydric hydroxy compound or its solvent diluted product, if necessary. , solvents, pigments (extender pigments, colored pigments, metallic pigments, etc.), ultraviolet absorbers, light stabilizers, radical stabilizers, yellowing inhibitors that suppress coloring during the baking process, coating surface conditioners, fluidity conditioners, Add additives such as pigment dispersants, antifoaming agents, thickeners, and film forming aids. Next, the above block polyisocyanate composition is added as a curing agent, and if necessary, a solvent is further added to adjust the viscosity. Next, a solvent-based resin composition can be obtained by stirring by hand or using a stirring device such as a Masella.

≪Resin film≫
The resin film of this embodiment is obtained by curing the above resin composition. The resin film of this embodiment has excellent curability, hardness, and strength at a low temperature of about 80°C.

The resin film of this embodiment is formed by applying the resin composition to a base material using a known method such as roll coating, curtain flow coating, spray coating, bell coating, electrostatic coating, etc., and curing by heating. You can get it by doing that.

From the viewpoint of energy saving and heat resistance of the base material, the heating temperature is preferably about 70°C or more and about 120°C or less, more preferably about 70°C or more and about 110°C or less, and even more preferably about 75°C or more and about 100°C or less.
From the viewpoint of energy saving and heat resistance of the base material, the heating time is preferably about 1 minute or more and about 60 minutes or less, and more preferably about 2 minutes or more and about 40 minutes or less.

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

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

The base material is one in which the surface of the above-mentioned metal material or the metal surface of a car body etc. formed from the above-mentioned metal material has been subjected to surface treatment such as phosphate treatment, chromate treatment, composite oxide treatment, etc. Furthermore, a coating film may be formed thereon. The base material on which the paint film is formed may be one that has been surface-treated as necessary and has an undercoat film formed thereon, such as a car body on which an undercoat film has been formed using electrodeposition paint. good. The base material may be one obtained by subjecting the surface of the above-mentioned plastic material or the surface of a plastic such as an automobile part molded from the above-mentioned metal material to surface treatment as desired. Further, the base material may be a combination of a plastic material and a metal material.

As shown in the examples below, the resin film of this embodiment is a 40 μm thick resin film obtained by curing the resin composition by heating it at 80°C for 30 minutes, and after storing it at 23°C for one week, add acetone to it. The gel fraction when immersed therein at 23° C. for 24 hours is preferably 83% by mass or more, more preferably 85% by mass or more, and even more preferably 86% by mass or more. When the gel fraction is at least the above lower limit, low-temperature curability can be improved. On the other hand, the upper limit of the gel fraction is not particularly limited, but may be, for example, 100% by mass. As a specific method for measuring the gel fraction, for example, a method shown in Examples described below can be used.

The resin film of this embodiment has a Koenig hardness at 23°C of a 40 μm thick resin film obtained by heating and curing the above resin composition on glass at 80°C for 30 minutes, as shown in the examples below. is preferably 40 times or more, more preferably 45 times or more, even more preferably 50 times or more, even more preferably 55 times or more, and even more preferably 60 times or more. preferable. When the Koenig hardness is greater than or equal to the above lower limit, a resin film with better hardness can be obtained. On the other hand, the upper limit of the Koenig hardness is not particularly limited, but can be set to 160 times, for example. As a specific method for measuring Koenig hardness, for example, a method shown in Examples described later can be used.

As shown in the Examples described below, the resin film of this embodiment is obtained by heating and curing the resin composition at 80° C. for 30 minutes, and the resin film has a thickness of 40 μm and has a maximum tensile stress of 12. It is preferably 0 MPa or more, more preferably 15 MPa or more, even more preferably 18 MPa or more, even more preferably 20 MPa or more, even more preferably 23 MPa or more, and even more preferably 25 MPa or more. It is particularly preferable. When the maximum tensile stress at 23° C. is equal to or higher than the above lower limit, a resin film with better strength can be obtained. On the other hand, the upper limit of the maximum tensile stress at 23° C. is not particularly limited, but may be, for example, 100 MPa. As a specific method for measuring the maximum tensile stress at 23° C., for example, a method shown in Examples described below can be used.

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

EXAMPLES Hereinafter, the present invention will be explained with reference to examples, but the present invention is not limited to the following examples.

Hereinafter, this embodiment will be described in more detail based on Examples and Comparative Examples, but this embodiment is not limited to the following Examples.

<Test items>
Regarding the block polyisocyanate compositions obtained in Examples and Comparative Examples, each physical property was measured and each evaluation was performed according to the methods shown below.

[Physical properties 1]
(Isocyanate group (NCO) content)
In order to measure the NCO content of polyisocyanate, polyisocyanate before blocking with a blocking agent was used as a measurement sample.

First, 2 g or more and 3 g or less of a measurement sample was accurately weighed in a flask (Wg). Next, 20 mL of toluene was added to dissolve the measurement sample. Next, 20 mL of a 2N toluene solution of di-n-butylamine was added, and after mixing, the mixture was left at room temperature for 15 minutes. Then, 70 mL of isopropyl alcohol was added and mixed. Next, this solution was titrated with a 1N hydrochloric acid solution (Factor F) as an indicator. The obtained titration value was defined as V2mL. The titration value obtained was then taken as V1 ml without the polyisocyanate sample. Next, the isocyanate group (NCO) content (% by mass) of the polyisocyanate was calculated from the following formula.

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

[Physical properties 2]
(Number average molecular weight and weight average molecular weight)
The number average molecular weight and weight average molecular weight are the number average molecular weight and weight average molecular weight based on polystyrene as measured by gel permeation chromatography (GPC) using the following apparatus. In order to measure the number average molecular weight of polyisocyanate, polyisocyanate before blocking with a blocking agent was used as a measurement sample. Moreover, regarding the weight average molecular weight, the block polyisocyanate composition or the polyhydric hydroxy compound was used as a measurement sample as it was. The measurement conditions are shown below.

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

[Physical properties 3]
(Average number of isocyanate functional groups)
The average number of isocyanate functional groups (average number of NCOs) of the polyisocyanate was determined by the following formula. In the formula, "Mn" is the number average molecular weight of the polyisocyanate before blocking with a blocking agent, and the value measured in "Physical Properties 2" above was used. "NCO content" is the isocyanate group content of the polyisocyanate measured before blocking with a blocking agent, and the value calculated in "Physical Properties 1" above was used.

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

[Physical properties 4]
(Solid content of block polyisocyanate composition)
The solid content of the block polyisocyanate composition was determined as follows.
First, an aluminum plate with a bottom diameter of 38 mm was accurately weighed. Next, about 1 g of the block polyisocyanate compositions produced in Examples and Comparative Examples was placed on an aluminum plate and accurately weighed (W1). Next, the block polyisocyanate composition was adjusted to have a uniform thickness. Next, the block polyisocyanate composition placed on the aluminum plate was kept in an oven at 105°C for 1 hour. Next, after the aluminum dish reached room temperature, the block polyisocyanate composition remaining in the aluminum dish was accurately weighed (W2). Next, the solid content (mass %) of the block polyisocyanate composition was calculated from the following formula.

Solid content (mass%) of block polyisocyanate composition = W2/W1×100

[Physical properties 5]
(Hydroxyl value)
The hydroxyl value of the polyhydric hydroxy compound was measured and calculated by potentiometric titration. Moreover, the hydroxyl value is a value based on the solid content in the polyhydric hydroxy compound.

[Physical properties 6]
(Glass transition temperature Tg)
The glass transition temperature of a polyhydric hydroxy compound is determined by removing the organic solvent and water in the polyhydric hydroxy compound solution under reduced pressure, drying it in vacuum, and measuring the heating rate using a differential scanning calorimetry (DSC) measuring device. The value measured under the condition of 5° C./min was used as the glass transition temperature.

[Production of resin composition 1]
The polyhydric hydroxy compound OHP1 and each blocked isocyanate composition are blended so that the ratio of the molar amount of isocyanate groups to the molar amount of hydroxyl groups (isocyanate group/hydroxyl group) is 1, and further 2-propanol is blended, A resin composition was obtained by adjusting the solid content to 35% by mass.

[Production of resin composition 2]
Polyhydric hydroxy compound OHP1 and each block isocyanate composition are blended so that the ratio of the molar amount of isocyanate groups to the molar amount of hydroxyl groups (isocyanate group/hydroxyl group) is 1, and butyl acetate is further blended to form a solid A resin composition was obtained by adjusting the amount to be 35% by mass.

[Evaluation 1]
(Storage stability)
The initial viscosity and the viscosity of the resin composition obtained in the above "Production of resin composition 1" after storage at 40° C. for 10 days were measured (viscosity meter: RE-85R manufactured by Toki Sangyo Co., Ltd.). Then, the ratio of the viscosity after storage to the initial viscosity was calculated. The storage stability was evaluated based on the ratio of the calculated viscosity after storage to the initial viscosity according to the following evaluation criteria.

(Evaluation criteria)
○: Ratio of viscosity after storage to initial viscosity is 2.0 or less △: Ratio of viscosity after storage to initial viscosity is more than 2.0 and 3.0 or less ×: Gelation

[Evaluation 2]
(Low temperature curability: gel fraction)
The resin composition obtained in the above "Production of resin composition 2" was coated on a polypropylene (PP) plate to a dry film thickness of 40 μm, and then heated and dried at 80° C. for 30 minutes to obtain a resin film. The obtained resin film was stored at room temperature (23° C.) for one week, and the gel fraction was measured. The gel fraction was determined as the percentage (mass %) of the undissolved partial mass when the resin film was immersed in acetone at 23° C. for 24 hours divided by the mass before immersion. In addition, those having a gel fraction of 83% by mass or more were evaluated as good.

[Rating 3]
(Koenig hardness)
The resin composition obtained in the above "Production of resin composition 2" was coated on a glass plate to a dry film thickness of 40 μm, and then heated and dried at 80° C. for 30 minutes to obtain a resin film. The Koenig hardness (times) of the obtained resin film was measured in a 23° C. environment using a Koenig hardness tester (Pendulum hardness tester manufactured by BYK Gardner). In addition, those having a Koenig hardness of 40 times or more were evaluated as good.

[Rating 4]
(Strength: maximum tensile stress)
The resin composition obtained in the above "Production of resin composition 2" was coated on a polypropylene (PP) plate to a dry film thickness of 40 μm, and then heated and dried at 80° C. for 30 minutes to obtain a resin film. The obtained resin film was cut to a width of 10 mm and a length of 40 mm, set so that the distance between the chucks was 20 mm, and a tensile test was conducted at a speed of 20 mm/min in an environment of 23°C. The maximum point stress at that time was defined as the maximum tensile stress. Note that those with a maximum tensile stress of 12.0 MPa or more were evaluated as good.

<Synthesis of polyisocyanate>
[Synthesis example 1]
(Synthesis of polyisocyanate P-1)
In a four-necked flask equipped with a thermometer, stirring blade, and reflux condenser, under a nitrogen stream, 100 parts by mass of HDI, and a polyester polyol (polycaprolactone triol) derived from a trihydric alcohol and ε-caprolactone. (Manufactured by Daicel Chemical Co., Ltd., "Plaxel 303" (trade name), average number of hydroxyl functional groups: 3, number average molecular weight 300): 5.3 parts by mass was charged, and the temperature inside the reactor was maintained at 89 ° C. for 1 hour while stirring. A urethanization reaction was performed. Thereafter, the temperature inside the reactor was maintained at 65° C., the isocyanurate catalyst tetramethylammonium caprate was added, and when the yield reached 52% by mass, phosphoric acid was added to stop the reaction. After filtering the reaction solution, unreacted HDI was removed using a thin film evaporator to obtain an isocyanurate-type polyisocyanate (hereinafter sometimes referred to as "polyisocyanate P-1"). The NCO content of the obtained polyisocyanate P-1 was 18.5% by mass, the number average molecular weight was 1225, and the average number of isocyanate groups was 5.4. Furthermore, ¹ H-NMR analysis was conducted on the obtained polyisocyanate P-1, and the presence of isocyanurate groups was confirmed.

[Synthesis example 2]
(Synthesis of polyisocyanate P-2)
In a four-necked flask equipped with a thermometer, stirring blade, and reflux condenser, under a nitrogen stream, 81 parts by mass of HDI, 19 parts by mass of IPDI, and a trihydric alcohol, trimethylolpropane (average hydroxyl functional Radix number: 3, molecular weight: 134): 3.35 parts by mass was charged, and the temperature inside the reactor was maintained at 90° C. for 1 hour with stirring to carry out a urethanization reaction. Thereafter, the temperature inside the reactor was maintained at 80° C., 0.012 parts by mass of isocyanurate catalyst tetramethylammonium caprate was added, and when the yield reached 44% by mass, phosphoric acid was added to stop the reaction. After filtering the reaction solution, unreacted HDI and IPDI were removed using a thin film evaporator to obtain an isocyanurate-type polyisocyanate (hereinafter sometimes referred to as "polyisocyanate P-2"). The NCO content of the obtained polyisocyanate P-2 was 18.8% by mass, the number average molecular weight was 1190, and the average number of isocyanate groups was 5.3. Furthermore, ¹ H-NMR analysis was conducted on the obtained polyisocyanate P-2, and the presence of isocyanurate groups was confirmed.

[Synthesis example 3]
(Synthesis of polyisocyanate P-3)
In a four-necked flask equipped with a thermometer, a stirring blade, and a reflux condenser, under a nitrogen stream, 70 parts by mass of HDI, 30 parts by mass of IPDI, and a trihydric alcohol, trimethylolpropane (average hydroxyl functional Radix number: 3, molecular weight: 134): 2.9 parts by mass was charged, and the temperature inside the reactor was maintained at 90° C. for 1 hour while stirring to perform a urethanization reaction. Thereafter, the temperature inside the reactor was maintained at 80° C., 0.012 parts by mass of isocyanurate catalyst tetramethylammonium caprate was added, and when the yield reached 44% by mass, phosphoric acid was added to stop the reaction. After filtering the reaction solution, unreacted HDI and IPDI were removed using a thin film evaporator to obtain an isocyanurate-type polyisocyanate (hereinafter sometimes referred to as "polyisocyanate P-3"). The NCO content of the obtained polyisocyanate P-3 was 18.8% by mass, the number average molecular weight was 1135, and the average number of isocyanate groups was 5.1. Furthermore, ¹ H-NMR analysis was conducted on the obtained polyisocyanate P-3, and the presence of isocyanurate groups was confirmed.

[Synthesis example 4]
(Synthesis of polyisocyanate P-4)
In a four-necked flask equipped with a thermometer, stirring blade, and reflux condenser, 100 parts by mass of HDI was charged under a nitrogen stream, and the temperature inside the reactor was maintained at 62°C while stirring, and trimethylbenzylammonium hydroxide was added. After 4.5 hours, when the conversion rate reached 40% by mass, 0.02 parts by mass of phosphoric acid was added to stop the reaction. After filtering the reaction solution, unreacted HDI was removed using a thin film evaporator to obtain an isocyanurate type polyisocyanate (hereinafter sometimes referred to as "polyisocyanate P-4"). The NCO content of the obtained polyisocyanate P-4 was 21.8% by mass, the number average molecular weight was 670, and the average number of isocyanate groups was 3.43. Furthermore, ¹ H-NMR analysis was conducted on the obtained polyisocyanate P-4, and the presence of isocyanurate groups was confirmed.

<Production of block polyisocyanate composition>
[Example 1]
(Manufacture of block polyisocyanate composition BL-a1)
In a four-necked flask equipped with a thermometer, stirring blade, and reflux condenser, 100 parts by mass of polyisocyanate P-1 obtained in Synthesis Example 1 and diisopropyl malonate (hereinafter referred to as "B1") were added under a nitrogen stream. 45 mol% of di-tert-butyl malonate (hereinafter sometimes referred to as "B2") based on 100 mol% of isocyanate groups, and 55 mol% of di-tert-butyl malonate (hereinafter sometimes referred to as "B2") based on 100 mol% of isocyanate groups. %, and further dipropylene glycol dimethyl ether (DPDM) was added to adjust the solid content to 60% by mass. Next, while stirring, 1.0 parts by mass of a methanol solution containing sodium methylate (28% by mass based on the total mass of the solution) was added dropwise, and the outer bath was adjusted so that the solution temperature was 52 ° C. Blocking reaction was carried out at 52°C for 6 hours or more. After confirming the disappearance of the isocyanate group peak by infrared spectroscopy (IR), it was cooled to 40°C, and aluminum tris(acetylacetonate) (hereinafter referred to as "AcAc/AL") was added to 100 parts by mass of the block polyisocyanate. ): 0.20 parts by mass and acetylacetone (hereinafter sometimes abbreviated as "AcAc"): 0.015 parts by mass were added and mixed to obtain a block polyisocyanate composition. . The obtained block polyisocyanate composition had a solid content of 60.0% by mass and a weight average molecular weight of 1.9×10 ⁴ .

[Examples 2 to 13 and Comparative Examples 1 to 5]
(Production of block polyisocyanate compositions BL-a2 to BLP-a13 and BL-b1 to BL-b5)
Using the same method as in Example 1, except that the type and amount of polyisocyanate, the type and amount of blocking agent, and the amount of metal chelate and acetylacetone were as shown in Tables 1 to 4, each A blocked polyisocyanate composition was produced.

[Example 14]
(Manufacture of block polyisocyanate composition BL-a14)
100 parts by mass of polyisocyanate P-2 obtained in Synthesis Example 2, methoxypolyethylene glycol (MPG-081, ethylene oxide) were placed in a four-necked flask equipped with a thermometer, stirring blade, and reflux condenser under a nitrogen stream. Repeating units: 15, manufactured by Nippon Nyukazai Co., Ltd.): 0.5 mol% based on 100 mol% of isocyanate groups of polyisocyanate P-2, 2-ethylhexyl acid phosphate (manufactured by Johoku Kagaku Kogyo Co., Ltd.) 0.008 parts by mass of "JP-508T" (trade name) and 54.2 parts by mass of dipropylene glycol dimethyl ether (DPDM) were mixed and reacted at 120° C. for 2 hours. The reaction solution was cooled to 40°C, and diisopropyl malonate (B1) was added at 65 mol% based on 100 mol% of isocyanate groups, and di-tert-butyl malonate (B2) was added at 35 mol% based on 100 mol% of isocyanate groups. The solid content was adjusted to 60% by mass by adding dipropylene glycol dimethyl ether (DPDM). Next, while stirring, 1.0 parts by mass of a methanol solution containing sodium methylate (28% by mass based on the total mass of the solution) was added dropwise, and the outer bath was adjusted so that the solution temperature was 52 ° C. The blocking reaction was carried out at 52°C for 6 hours or more. After confirming the disappearance of the isocyanate group peak by infrared spectroscopy (IR), it was cooled to 40°C, and aluminum tris(acetylacetonate) (AcAc/AL): 0.50 was added to 100 parts by mass of block polyisocyanate. Parts by mass and 0.037 parts by mass of acetylacetone (AcAc) were added and mixed to obtain a block polyisocyanate composition. The obtained block polyisocyanate composition had a solid content of 60.0% by mass and a weight average molecular weight of 1.8×10 ⁴ .

<Production of polyhydric hydroxy compound>
[Manufacture example 1]
(Production of polyvalent hydroxy compound OHP1)
29 parts by mass of propylene glycol monomethyl ether was charged into a four-neck flask equipped with a stirrer, a thermometer, a cooling tube, and a nitrogen gas inlet, and the temperature was raised to 110° C. under nitrogen gas ventilation. After reaching 110°C, the nitrogen gas ventilation was stopped, and 2-hydroxyethyl methacrylate: 22.3 parts by mass, methyl methacrylate: 8.0 parts by mass, butyl acrylate: 26.1 parts by mass, styrene: 42.3 parts by mass. 1.3 parts by mass of acrylic acid, and 1.9 parts by mass of 2,2'-azobis(isobutyronitrile) were added dropwise over 5.5 hours. Next, the mixture was stirred at 115° C. for 3 hours while flowing nitrogen gas, cooled to 30° C., and then the solvent was removed using an evaporator. Next, butyl acetate was added to obtain a solution of polyhydric hydroxy compound OHP1, which is an acrylic polyol resin, with a solid content of 60% by mass. The polyvalent hydroxy compound OHP1 had a weight average molecular weight Mw of 2.73×10 ⁴ , a hydroxyl value of 139 mgKOH/g, and a glass transition temperature Tg of 29.8°C.

In Tables 1 to 4 below, abbreviations indicate the following compounds.

(metal chelate)
AcAc/AL: aluminum tris (acetylacetonate)

(solvent)
AcAc: acetylacetone

(blocking agent)
B1: Diisopropyl malonate B2: Di-tert-butyl malonate

From Tables 1 to 4, block polyisocyanate compositions BL-a1 to BL-a14 (Examples 1 to 14) had good storage stability when made into resin compositions, and when made into coating films. It had excellent curability, hardness and strength at a low temperature of about 80°C.
In addition, in a comparison of block polyisocyanate compositions BL-a1 to BL-a6 (Examples 1 to 6) with different metal chelate contents, the higher the metal chelate content, the higher the 80% There was a tendency for the curability and hardness to be better at a low temperature of about ℃.
In addition, a comparison of block polyisocyanate compositions BL-a4 (Example 4) and BL-a7 (Example 7) with different molar ratios of blocking agent B1 to blocking agent B2 (B1/B2), and BL-a5 ( In a comparison of Example 5), BL-a8 (Example 8), and BL-a9 (Example 9), the smaller the molar ratio of B1/B2, that is, the higher the blending ratio of B2, the better the coating film. There was a tendency for the curability, hardness, and strength to be better at low temperatures of about 80°C.
In a comparison of block polyisocyanate compositions BL-a7 and BL-a12 (Examples 7 and 12) using different types of polyisocyanates, it was found that the smaller the average number of isocyanate groups in the polyisocyanate, the lower the hardness and strength when formed into a coating film. On the other hand, the larger the average number of isocyanate groups in the polyisocyanate, the better the curability at a low temperature of about 80° C. when formed into a coating film.
The blocked polyisocyanate composition BL-a2 (Example 2) using both the blocking agent B1 and the blocking agent B2 has the following characteristics compared to the blocked polyisocyanate composition BL-a13 (Example 13) using only the blocking agent B2. The storage stability when made into a resin composition and the strength when made into a coating film were better.

On the other hand, in block polyisocyanate compositions BL-b1 to BL-b2 (Comparative Examples 1 and 2) in which the content of metal chelate is more than 7 parts by mass with respect to 100 parts by mass of block polyisocyanate, metal chelate remains undissolved. was. Therefore, various evaluations could not be performed.
In addition, a blocked polyisocyanate composition BL-b3 (Comparative Example 3) containing no metal chelate and using only a malonic acid ester having a secondary alkyl group as a blocking agent, blocking only a malonic acid ester having a secondary alkyl group The blocked polyisocyanate composition BL-b4 (Comparative Example 4) used as a blocking agent, and the average number of isocyanate groups of the polyisocyanate was less than 3.5, and only a malonic acid ester having a secondary alkyl group was used as a blocking agent. Block polyisocyanate composition BL-b5 (Comparative Example 5) had good storage stability when made into a resin composition, but the curability and hardness at a low temperature of about 80°C when made into a coating film. and the strength was poor.

The block polyisocyanate composition of the present embodiment has good storage stability when made into a resin composition, and has good curability, hardness and strength at a low temperature of about 80°C when made into a coating film. A block polyisocyanate composition having excellent properties can be provided.

Claims (19)

A blocked polyisocyanate derived from a polyisocyanate and a blocking agent containing a malonic acid ester having a tertiary alkyl group;
A block polyisocyanate composition comprising one or more metal chelates,
The polyisocyanate has an average number of isocyanate groups of 4.7 or more and 8 or less , has an isocyanurate group, and has an average hydroxyl group functionality and one or more diisocyanates selected from the group consisting of aliphatic diisocyanates and alicyclic diisocyanates. A polyisocyanate derived from a polyol having a base number of 2.9 or more and 8.0 or less ,
A block polyisocyanate composition, wherein the content of the metal chelate is 0.05 parts by mass or more and 7 parts by mass or less with respect to 100 parts by mass of the block polyisocyanate. The block polyisocyanate composition according to claim 1 , wherein the metal chelate is a metal chelate selected from the group consisting of aluminum chelate and titanium chelate. The block polyisocyanate composition according to claim 1 or 2 , wherein the metal chelate is aluminum tris(acetylacetonate). 4. The blocked polyisocyanate composition according to claim 3 , further comprising acetylacetone. The block polyisocyanate composition according to any one of claims 1 to 4 , wherein the weight average molecular weight Mw of the block polyisocyanate composition is 3.0×10 ³ or more. The blocked polyisocyanate composition according to any one of claims 1 to 5 , wherein a part of the blocked polyisocyanate has a structural unit derived from a hydrophilic compound. The block polyisocyanate composition according to claim 6 , wherein the hydrophilic compound contains one or more compounds selected from the group consisting of nonionic compounds and anionic compounds. The block polyisocyanate composition according to any one of claims 1 to 7 , wherein the malonic acid ester having a tertiary alkyl group is di-tert-butyl malonate. The blocked polyisocyanate composition according to any one of claims 1 to 8 , wherein the blocking agent further contains a malonic acid ester having a secondary alkyl group. The block polyisocyanate composition according to claim 9 , wherein the malonic acid ester having a secondary alkyl group is diisopropyl malonate. A resin composition comprising the blocked polyisocyanate composition according to any one of claims 1 to 10 and a polyhydric hydroxy compound. The resin composition according to claim 11 , wherein the polyhydric hydroxy compound has a glass transition temperature Tg of 0°C or more and 100°C or less. The resin composition according to claim 11 or 12 , wherein the polyvalent hydroxy compound has a weight average molecular weight Mw of 5.0×10 ³ or more and 2.0×10 ⁵ or less. The resin composition according to any one of claims 1 1 to 1 3 , wherein the polyhydric hydroxy compound has a hydroxyl value of 30 mgKOH/g or more and 250 mgKOH/g or less. The resin composition according to any one of claims 11 to 14 , wherein the content of the blocked polyisocyanate is 1 part by mass or more and 200 parts by mass or less, based on 100 parts by mass of the polyhydric hydroxy compound. A resin film obtained by curing the resin composition according to any one of claims 11 to 15 . A resin film with a thickness of 40 μm obtained by heating and curing the resin composition at 80° C. for 30 minutes has a gel fraction of 83% by mass when immersed in acetone for 24 hours at 23° C. after being stored at 23° C. for 1 week. The resin film according to claim 16 , which is above. 18. The resin film according to claim 16 or 17, wherein a resin film having a thickness of 40 μm obtained by heating and curing the resin composition on glass at 80° C. for 30 minutes has a Koenig hardness of 40 times or more at 23° C. resin film. Any one of claims 16 to 18, wherein a resin film having a thickness of 40 μm obtained by heating and curing the resin composition at 80° C. for 30 minutes has a maximum tensile stress of 12.0 MPa or more at 23 ° C. The resin film described in .