JP7216605B2 - Polyisocyanate composition, blocked polyisocyanate composition, coating composition, coating film and coating - Google Patents

Description

The present invention relates to polyisocyanate compositions, blocked polyisocyanate compositions, coating compositions, coatings and coatings.

Conventionally, polyisocyanate compositions and blocked polyisocyanates derived from 1,6-diisocyanatohexane (also referred to as "hexamethylene diisocyanate"; hereinafter sometimes abbreviated as "HDI") having isocyanurate groups The composition is used as a material for paints and the like (see, for example, Patent Documents 1 to 3, etc.).

Japanese Patent Publication No. 45-027982 JP-A-55-038380 JP-A-57-150677

However, conventional polyisocyanate compositions described in Patent Documents 1 to 3, etc., and coating compositions using the blocked polyisocyanate compositions obtained therefrom, are hardened when thick or under high humidity. , Waki (foaming) and cloudiness may occur, and there is plenty of room for improvement.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a polyisocyanate composition which is excellent in appearance when formed into a coating film even under high humidity curing conditions. A blocked polyisocyanate composition, a coating composition, a coating film and a coating using the polyisocyanate composition are provided.

That is, the present invention includes the following aspects.
The polyisocyanate composition according to the first aspect of the present invention is a polyisocyanate composition having structural units derived from the following components (a) to (c) and having an isocyanurate group,
(a) 1,6-diisocyanatohexane;
(b) a polypropylene polyol;
(c) a monoalcohol;
The (a) trimer consisting of 3 molecules of 1,6-diisocyanatohexane and having an isocyanurate group has a content of 30% by mass or more and 50% by mass or less with respect to the total mass of the polyisocyanate composition,
The content of the structural unit derived from the (b) polypropylene polyol is 5% by mass or more and 15% by mass or less with respect to the mass of the structural unit derived from the (a) 1,6-diisocyanatohexane ,
The content of the (c) monoalcohol-derived structural unit is 1.0% by mass or more and 5.0% by mass or less with respect to the mass of the (a) 1,6-diisocyanatohexane-derived structural unit. can be,
The (c) monoalcohol has 1 or more and 9 or less carbon atoms .

The number average molecular weight of the structural unit derived from the (b) polypropylene polyol may be 300 or more and 1000 or less.
The isocyanate group content may be 15% by mass or more and 22% by mass or less.
The number of functional groups of the isocyanate group may be 3.0 or more and 4.5 or less.

The blocked polyisocyanate composition according to the second aspect of the present invention is configured by blocking some or all of the isocyanate groups of the polyisocyanate composition according to the first aspect with a pyrazole compound.

A coating composition according to a third aspect of the present invention contains the polyisocyanate composition according to the first aspect or the blocked polyisocyanate composition according to the second aspect.

The coating film according to the third aspect of the present invention is obtained by curing the coating composition according to the third aspect.

A coated article according to a third aspect of the present invention comprises a molded article and the coating film according to claim 8 coated on the surface of the molded article.

According to the polyisocyanate composition of the above aspect, it is possible to provide a polyisocyanate composition which is excellent in appearance when formed into a coating film even under high humidity curing conditions. The blocked polyisocyanate composition of the above aspect is derived from the above polyisocyanate composition and has excellent appearance when used as a coating film. The coating composition of the above aspect contains the polyisocyanate composition or the blocked polyisocyanate composition, and has excellent appearance when formed into a coating film. The coating film and the coating of the above aspect are obtained using the coating composition and have excellent appearance.

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

<<Polyisocyanate composition>>
The polyisocyanate composition of the present embodiment has structural units derived from the following components (a) and (b).
(a) 1,6-diisocyanatohexane (HDI);
(b) polypropylene polyol

That is, the polyisocyanate composition of the present embodiment is a reaction product of (a) HDI and (b) polypropylene polyol. The polyisocyanate composition of the present embodiment uses (a) HDI as a raw material, so that a flexible and tough coating film having a low viscosity can be obtained.

Moreover, the polyisocyanate composition of this embodiment has an isocyanurate group. Since the polyisocyanate composition of the present embodiment has an isocyanurate group, a coating film having excellent heat resistance can be obtained. In addition, the isocyanurate group is a group represented by the following formula (1).

In addition, the polyisocyanate composition of the present embodiment contains (a) a trimer consisting of 3 molecules of HDI and having an isocyanurate group (hereinafter sometimes simply abbreviated as "trimer"). The lower limit of the trimer content is 30% by mass, preferably 35% by mass, more preferably 40% by mass, relative to the total mass of the polyisocyanate composition. On the other hand, the upper limit of the trimer content is 50% by mass, preferably 48% by mass, more preferably 45% by mass, relative to the total mass of the polyisocyanate composition.
That is, the content of the trimer having an isocyanurate group is 30% by mass or more and 50% by mass or less, preferably 35% by mass or more and 48% by mass or less, relative to the total mass of the polyisocyanate composition, and 40% by mass. % or more and 45 mass % or less is more preferable.
When the trimer content is within the above range, the polyisocyanate composition has better curability and a lower viscosity.
The trimer content can be determined by measuring a polyisocyanate composition containing less than 1% by mass of solvent by gel permeation chromatography (GPC). Specifically, it can be measured according to the method described in the examples below.

Further, in the polyisocyanate composition of the present embodiment, the lower limit of the content of (b) structural units derived from polypropylene polyol is 5% by mass with respect to the mass of (a) structural units derived from HDI. , is preferably 6% by mass, more preferably 8% by mass. On the other hand, (b) the upper limit of the content of structural units derived from polypropylene polyol is 15% by mass, preferably 13% by mass, and 12% by mass, based on the mass of (a) structural units derived from HDI. is more preferred.
That is, the content of (b) the structural unit derived from polypropylene polyol is 5% by mass or more and 15% by mass or less, and 6% by mass or more and 13% by mass, with respect to the mass of (a) the structural unit derived from HDI. The following is preferable, and 8% by mass or more and 12% by mass or less is more preferable.
(B) When the content of the structural unit derived from polypropylene polyol is within the above range, the coating is more excellent in hardness, less prone to popping and whitening when cured under high humidity conditions, and has an excellent appearance. A membrane is obtained. The term "waki" as used herein refers to a phenomenon in which small bubble-like swellings and holes are generated when the coating film is cured, and is also called foaming.
(b) The content of structural units derived from polypropylene polyol can be calculated from the synthesis conditions as shown in the examples described later. If the synthesis conditions are unknown, ¹ H-NMR can be used to calculate the ratio of the integrated value of the methyl group of the polypropylene polyol to the integrated value of the methylene group of HDI, thereby obtaining (b) derived from the polypropylene polyol The content of the constituent units can be obtained.

As the (b) polypropylene polyol used in the polyisocyanate composition of the present embodiment, polypropylene glycol or polypropylene triol is preferable, and polypropylene glycol is more preferable. By using these polypropylene polyols, popping and whitening can be more effectively suppressed when the coating film is cured under high humidity conditions, and more excellent curability can be imparted.

(b) The lower limit of the molecular weight of the polypropylene polyol is preferably 300, more preferably 350, and even more preferably 400. On the other hand, the upper limit of the molecular weight of (b) polypropylene polyol is preferably 1000, more preferably 800, and even more preferably 600.
That is, the molecular weight of the (b) polypropylene polyol is preferably 300 or more and 1000 or less, more preferably 350 or more and 800 or less, and even more preferably 400 or more and 600 or less.
When the molecular weight of the polypropylene polyol is within the above range, it is possible to more effectively suppress popping and whitening when cured under high humidity conditions, and further increase the hardness of the resulting coating film. can.

The polyisocyanate composition of the present embodiment may further have (c) a structural unit derived from a monoalcohol.
(c) The lower limit of the content of structural units derived from monoalcohol is preferably 1.0% by mass, more preferably 1.2% by mass, relative to the mass of (a) structural units derived from HDI, 1.4% by mass is more preferred. On the other hand, (c) the upper limit of the content of structural units derived from monoalcohol is preferably 5.0% by mass, more preferably 4.5% by mass, relative to the mass of (a) structural units derived from HDI. Preferably, 4.0% by mass is more preferable.
That is, the content of (c) the monoalcohol-derived structural unit is preferably 1.0% by mass or more and 5.0% by mass or less with respect to the mass of the (a) HDI-derived structural unit, and 1.2% by mass. It is more preferably 4.5% by mass or less, and even more preferably 1.4% by mass or more and 4.0% by mass or less.
(c) When the content of structural units derived from a monoalcohol is within the above range, the polyisocyanate composition is excellent in crosslinkability, has a lower viscosity, and is easy to handle.
In addition, the content of (c) structural units derived from monoalcohol can be calculated from the synthesis conditions as shown in Examples described later. If the synthesis conditions are unknown, ¹ H-NMR can be used to calculate the ratio of the integrated value of the terminal methyl group of the monoalcohol to the integrated value of the methylene group of HDI. It is possible to obtain the content of the structural unit to be used.

As the (c) monoalcohol used in the polyisocyanate composition of the present embodiment, a monoalcohol having a linear or branched alkyl group can be used.
(c) As for the lower limit of carbon number of monoalcohol, 1 is preferred, 2 is more preferred, and 3 is still more preferred. On the other hand, the upper limit of the number of carbon atoms in (c) the monoalcohol is preferably 9, more preferably 7, and even more preferably 5.
That is, the carbon number of (c) monoalcohol is preferably 1 to 9, more preferably 2 to 7, and even more preferably 3 to 5.
(c) When the number of carbon atoms in the monoalcohol is within the above range, the hardness of the coating composition using the polyisocyanate composition is superior, and popping and whitening occur more when cured under high humidity conditions. It is difficult to remove, and a coating film with a better appearance can be obtained.
The number of carbon atoms in the (c) monoalcohol can be determined by analyzing the polyisocyanate composition with ¹ H-NMR, ¹³ C-NMR, or the like.
Preferred (c) monoalcohols include, for example, n-propanol, n-butanol, isobutanol, n-pentanol, n-hexanol, 2-ethylhexanol and the like.

The lower limit of the isocyanate group content (NCO content) of the polyisocyanate composition of the present embodiment is preferably 15.0% by mass, more preferably 16.0% by mass, under the condition that the nonvolatile content is 98% by mass or more. 18.0% by mass is more preferable. On the other hand, the upper limit of the NCO content is preferably 22.0% by mass, more preferably 21.0% by mass, and even more preferably 20.0% by mass, under the condition that the non-volatile content is 98% by mass or more.
That is, the NCO content is preferably 15.0% by mass or more and 22.0% by mass or less, more preferably 16.0% by mass or more and 21.0% by mass or less, under the condition that the non-volatile content is 98% by mass or more. 0% by mass or more and 20.0% by mass or less is more preferable.
When the NCO content is at least the above lower limit, the viscosity of the polyisocyanate composition can be made lower. When the NCO content is equal to or less than the above upper limit, the crosslinkability of the polyisocyanate composition can be further increased.
The NCO content can be determined by back titration with 1N hydrochloric acid after neutralizing the isocyanate groups of the polyisocyanate composition with excess 2N amine. The non-volatile content in the polyisocyanate composition can be determined from the remaining amount after heating the polyisocyanate composition at 105° C. for 3 hours. Specifically, it can be measured according to the method described in the examples below.

The lower limit of the number of functional groups of the isocyanate groups in the polyisocyanate composition of the present embodiment is preferably 3.0, more preferably 3.1, and even more preferably 3.2. On the other hand, the upper limit of the number of functional groups of the isocyanate group is preferably 4.5, more preferably 4.3, and even more preferably 4.1.
That is, the number of functional groups of the isocyanate group is preferably 3.0 or more and 4.5 or less, more preferably 3.1 or more and 4.3 or less, and even more preferably 3.2 or more and 4.1 or less.
If the number of functional groups of the isocyanate group is equal to or less than the above upper limit, the viscosity of the polyisocyanate composition will be lower, making it easier to handle.
The number of functional groups of the isocyanate group can be determined by the following formula using the above isocyanate group content after measuring the number average molecular weight by GPC.

Number of functional groups of isocyanate group = NCO content (%) x number average molecular weight/42

The lower limit of the number average molecular weight of the solid content in the polyisocyanate composition of the present embodiment is preferably 600, more preferably 650, and even more preferably 700, under the condition that the non-volatile content is 98% by mass or more. On the other hand, the upper limit of the number average molecular weight is preferably 1,100, more preferably 1,000, and even more preferably 900 under the condition that the non-volatile content is 98% by mass or more.
That is, the number average molecular weight is preferably 600 or more and 1100 or less, more preferably 650 or more and 1000 or less, and even more preferably 700 or more and 900 or less, under the condition that the non-volatile content is 98% by mass or more.
When the number average molecular weight is within the above range, the glossiness of the resulting coating film can be improved and the yield of the polyisocyanate composition can be increased.
The number average molecular weight can be determined by GPC. Specifically, it can be measured according to the method described in the examples below.

The lower limit of the viscosity at 23 ° C. of the solid content in the polyisocyanate composition of the present embodiment is preferably 3,000 mPa s, more preferably 3,500 mPa s, under the condition that the nonvolatile content is 98% by mass or more. ,000 mPa·s is more preferable. On the other hand, the upper limit of the viscosity at 23° C. is preferably 30,000 mPa·s, more preferably 25,000 mPa·s, and even more preferably 20,000 mPa·s under the condition of a non-volatile content of 98% by mass or more.
That is, the viscosity at 23 ° C. is preferably 3,000 mPa s or more and 30,000 mPa s or less, more preferably 3,500 mPa s or more and 25,000 mPa s or less, under the condition of a nonvolatile content of 98% by mass or more. ,000 mPa·s or more and 20,000 mPa·s or less is more preferable.
By setting the viscosity of the polyisocyanate composition to the above lower limit or more, it is possible to more effectively suppress popping and whitening under high humidity conditions. The gloss of the coating film is further improved.
The viscosity can be measured using an E-type viscometer (manufactured by Tokimec).

The residual monomer concentration of the polyisocyanate composition of the present embodiment is preferably 2% by mass or less, more preferably 1.5% by mass or less, and even more preferably 1.0% by mass or less. When the residual monomer concentration is equal to or less than the above upper limit, the danger during handling is further reduced. The lower limit of the residual monomer concentration is not particularly limited because the lower the better.

<Method for producing polyisocyanate composition>
An example of the method for producing the polyisocyanate composition of the present embodiment will be described below.
As raw materials for the polyisocyanate composition of the present embodiment, it is preferable to use at least (a) HDI and (b) polypropylene glycol, and further use (c) monoalcohol. Alcohol compounds such as alkyl diols and polyoxyalkylene glycol monoalkyl esters can also be used together as auxiliary materials.
A polymerization catalyst is added to the raw materials (a) HDI and (b) polypropylene glycol and, if necessary, (c) monoalcohol and the auxiliary raw material, and the reaction is allowed to proceed until a predetermined degree of polymerization is reached. A polyisocyanate composition can be obtained by deactivating the polymerization catalyst and, if necessary, removing unreacted HDI.

Specific examples of the polymerization catalyst include compounds shown in (1) to (6) below.
(1) tetraalkylammonium hydroxides such as tetramethylammonium and tetraethylammonium, and organic weak acid salts of the tetraalkylammonium acetates, butyrates, decanoates and the like;
(2) Hydroxides of hydroxyalkylammonium such as tetramethylhydroxypropylammonium, trimethylhydroxyethylammonium, triethylhydroxypropylammonium and triethylhydroxyethylammonium, and acetates, butyrates, decanoates, etc. of the hydroxyalkylammonium weak organic acid salts;
(3) metal salts of alkylcarboxylic acids such as acetic acid, capric acid, octylic acid and myristic acid with alkali metals such as sodium and potassium; (4) alkylcarboxylic acids such as acetic acid, capric acid, octylic acid and myristic acid; , tin, zinc, lead, bismuth, zirconyl, zirconium and other metal salts;
(5) metal alcoholates such as sodium, potassium, bismuth, zirconium;
(6) Aminosilyl group-containing compounds such as hexamethyldidirasane

Among them, the above (1) or (2) is preferable from the viewpoint of catalytic efficiency, and (4) is preferable when it is desired to increase the ratio of allophanate groups.

The lower limit of the amount of polymerization catalyst used for HDI is not particularly limited, but is preferably 5 ppm, more preferably 10 ppm, and even more preferably 20 ppm. On the other hand, the upper limit of the amount of polymerization catalyst used is preferably 5000 ppm, more preferably 2000 ppm, and even more preferably 500 ppm.
That is, the amount of the polymerization 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 even more preferably 20 ppm or more and 500 ppm or less.
Reactivity is more excellent when the amount of the polymerization catalyst used is at least the above lower limit. On the other hand, when the amount of the polymerization catalyst used is equal to or less than the above upper limit, coloring and discoloration of the obtained polyisocyanate composition can be more effectively suppressed, and the reaction can be controlled.

The lower limit of the polymerization reaction temperature is not particularly limited, but is preferably 40°C, more preferably 50°C, and even more preferably 60°C. On the other hand, the upper limit of the polymerization reaction temperature is preferably 150°C, more preferably 120°C, and even more preferably 110°C.
That is, the polymerization reaction temperature is preferably 40° C. or higher and 150° C. or lower, more preferably 50° C. or higher and 120° C. or lower, and even more preferably 60° C. or higher and 110° C. or lower.
When the polymerization reaction temperature is equal to or higher than the above lower limit, the reaction rate is excellent. On the other hand, when the polymerization reaction temperature is equal to or lower than the above upper limit, coloring and discoloration of the obtained polyisocyanate composition can be more effectively suppressed.

When the polymerization reaction reaches the desired degree of polymerization, the polymerization reaction is stopped. The polymerization reaction is stopped by, for example, adding an acidic compound such as phosphoric acid, acidic phosphate, sulfuric acid, hydrochloric acid, or a sulfonic acid compound to the reaction solution to neutralize the polymerization reaction catalyst, or to thermally decompose it, chemically decompose it, or the like. It can be achieved by inactivating with After stopping the reaction, filtration is performed if necessary.

Since the reaction solution immediately after stopping the reaction usually contains unreacted HDI monomer, it is preferable to remove this by thin film evaporator, extraction, or the like. By performing such a post-treatment, the HDI monomer concentration contained in the polyisocyanate composition can be controlled to 2% by mass or less, preferably 1% by mass or less.

As another method for producing the polyisocyanate composition of the embodiment of the present application, for example, (a) a polymerization catalyst is added to HDI or an auxiliary material, the reaction is allowed to proceed until a predetermined degree of polymerization is reached, and the polymerization catalyst is added. After obtaining a polyisocyanate compound by deactivating and removing unreacted HDI, the obtained polyisocyanate compound is mixed with (b) polypropylene polyol or (c) monoalcohol, and is reacted with a catalyst or heat. Examples include a production method in which a urethanization reaction or an allophanatization reaction is performed.

The reaction between the polyisocyanate compound and polypropylene polyol or monoalcohol can be carried out with or without a solvent. When using a solvent, it is necessary to use a solvent that is inert to isocyanate groups. Examples of solvents include esters, ketones, aromatic compounds, and the like. Examples of esters include ethyl acetate and butyl acetate. Examples of ketones include methyl ethyl ketone and the like. Examples of aromatic compounds include toluene and xylene. Moreover, you may use a catalyst as needed. Examples of catalysts include organic metal salts, tertiary ammonium salts, alkali metal alcoholates, and the like. Examples of metals used in organic metal salts include tin, zinc, and lead. Examples of alkali metals include sodium and the like.

The lower limit of the reaction temperature between the polyisocyanate compound and polypropylene polyol or monoalcohol is generally -20°C, preferably 0°C, more preferably 30°C. On the other hand, the upper limit of the reaction temperature is 150°C, preferably 120°C, more preferably 100°C.
That is, the reaction temperature is -20°C or higher and 150°C or lower, preferably 0°C or higher and 120°C or lower, and more preferably 30°C or higher and 100°C or lower.
When the reaction temperature is within the above range, the reaction can be carried out at an appropriate reaction rate with less side reactions.

<<Blocked polyisocyanate composition>>
The blocked polyisocyanate composition of the present embodiment is configured by blocking some or all of the isocyanate groups of the above polyisocyanate composition with a pyrazole compound.

Specific examples of pyrazole compounds include pyrazole, 3,5-dimethylpyrazole, and 3-methylpyrazole.

The blocked polyisocyanate composition of the present embodiment may be configured by blocking some or all of the isocyanate groups with another blocking agent in addition to the pyrazole compound.
Other blocking agents include, for example, compounds shown in 1) to 6) below.
1) alcohols such as methanol, ethanol, propanol, butanol;
2) phenols such as phenol and cresol;
3) alkylphenols such as ethylphenol, propylphenol, hexylphenol;
4) active methylenes such as diemethyl malonate, diethyl malonate, dipropyl malonate, methyl acetoacetate and ethyl acetoacetate;
5) imidazoles such as imidazole and 2-imidazole;
6) Oximes such as formaldoxime, acetaldoxime, acetoxime, methylethylketoxime, cyclohexanone oxime

<Method for producing blocked polyisocyanate composition>
The blocked polyisocyanate composition of the present embodiment is obtained by reacting the polyisocyanate composition, the pyrazole-based compound, and, if necessary, another blocking agent.

The blocking agent reaction can be carried out with or without a solvent. When using a solvent, it is necessary to use a solvent that is inert to isocyanate groups. Moreover, you may use a catalyst as needed. Examples of the solvent and catalyst include the same as those exemplified in the above "method for producing a polyisocyanate composition".

The lower limit of the reaction temperature between the polyisocyanate composition and the blocking agent such as the pyrazole compound is generally -20°C, preferably 0°C, more preferably 30°C. On the other hand, the upper limit of the reaction temperature is 150°C, preferably 120°C, more preferably 100°C.
That is, the reaction temperature is -20°C or higher and 150°C or lower, preferably 0°C or higher and 120°C or lower, and more preferably 30°C or higher and 100°C or lower.
When the reaction temperature is within the above range, the reaction can be carried out at an appropriate reaction rate with less side reactions.

≪Paint composition≫
The polyisocyanate composition or the blocked polyisocyanate composition is suitably used as a curing agent component of a coating composition. That is, the coating composition of the present embodiment contains the polyisocyanate composition or the blocked polyisocyanate composition.

The resin component used in the coating composition preferably contains a compound having two or more active hydrogens reactive with isocyanate groups in the molecule. Examples of compounds having two or more active hydrogens in the molecule include polyols, polyamines, and polythiols. Among them, polyol is preferable. Specific examples of polyols include polyester polyols, polyether polyols, acrylic polyols, polyolefin polyols, and fluorine-containing polyols.

As the polyol, acrylic polyol is preferable from the viewpoint of weather resistance, chemical resistance and hardness, and polyester polyol is preferable from the viewpoint of mechanical strength, oil resistance and pigment dispersibility. In particular, when used as a topcoat for automotive repair paints, acrylic polyols are preferred because weather resistance, chemical resistance, hardness and the like are important. On the other hand, when used as an intermediate coat, a base, or a plastic surface, mechanical strength, pigment dispersibility, etc. are important, so polyester polyols are preferred.

Although the hydroxyl value of the polyol is not particularly limited, it is usually 30 mgKOH/g or more and 200 mgKOH/g or less, and the acid value is 0 mgKOH/g or more and 30 mgKOH/g or less.
A hydroxyl value and an acid value can be measured according to JIS K1557.

The molar ratio of the isocyanate groups of the polyisocyanate composition or the blocked polyisocyanate composition to the hydroxyl groups of the polyol (NCO/OH ratio) is preferably 0.2 or more and 5.0 or less, more preferably 0.4 or more and 3.0 or less. It is preferably 0.5 or more and 2.0 or less. When the NCO/OH ratio is within the above range, a tougher coating film with higher smoothness can be obtained.

The coating composition of another embodiment, for example, does not contain a compound having two or more active hydrogens in the molecule, and contains a polyisocyanate composition or a blocked polyisocyanate composition and a catalyst for accelerating curing. Moisture-curable coating compositions are mentioned.

Specific examples of curing acceleration catalysts include metal salts and tertiary amines. Examples of metal salts include dibutyltin dilaurate, tin 2-ethylhexanoate, zinc 2-ethylhexanoate, cobalt salts and the like. Examples of tertiary amines include triethylamine, pyridine, methylpyridine, benzyldimethylamine, N,N-dimethylcyclohexylamine, N-methylpiperidine, pentamethyldiethylenetriamine, N,N'-endoethylenepiperazine, N,N' - dimethylpiperazine and the like.

The coating composition of the present embodiment can further contain a melamine-based curing agent such as a complete alkyl type, methylol type alkyl, or iminoki type alkyl, if necessary.

The coating composition of this embodiment can further contain an organic solvent. The organic solvent is preferably a compound that does not have functional groups that react with hydroxyl groups and isocyanate groups. Compounds compatible with the polyisocyanate composition are also preferred. Examples of such organic solvents include ester compounds, ether compounds, ketone compounds, aromatic compounds, ethylene glycol dialkyl ether compounds, polyethylene glycol dicarboxylate compounds, hydrocarbon solvents, which are generally used as paint solvents. Aromatic solvents and the like can be mentioned.

Depending on the purpose and application, the coating composition of the present embodiment may include, for example, a catalyst, a pigment, a leveling agent, an antioxidant, an ultraviolet absorber, a light stabilizer, a plasticizer, as long as the effects of the present embodiment are not impaired. , surfactants, and other additives used in the art.

<Method for producing paint composition>
When the coating composition of the present embodiment is a solvent-based coating composition, for example, first, a resin containing a compound having two or more active hydrogens in the molecule or a solvent dilution thereof, if necessary , Other resins, catalysts, pigments, leveling agents, antioxidants, ultraviolet absorbers, light stabilizers, plasticizers, additives such as surfactants are added to the above polyisocyanate composition or blocked polyisocyanate composition is added as a curing agent. Then, if necessary, a solvent is further added to adjust the viscosity. A solvent-based coating composition can then be obtained by stirring by hand or by using a stirring device such as a Masellar.

When the coating composition of the present embodiment is a moisture-curable coating composition that does not contain a compound having two or more active hydrogens in the molecule, for example, the above polyisocyanate composition or blocked polyisocyanate composition, or Add other resins, catalysts, pigments, leveling agents, antioxidants, UV absorbers, light stabilizers, plasticizers, surfactants, etc. to the solvent-diluted product, and if necessary, catalysts for accelerating curing. Add agent. Then, if necessary, a solvent is further added to adjust the viscosity. Then, the mixture is stirred by hand or by using a stirring device such as a mazeller to obtain a moisture-curable coating composition.

<Application of paint composition>
The coating composition of the present embodiment is not limited to the following, but can be used as a coating for roll coating, curtain flow coating, spray coating, bell coating, electrostatic coating, and the like. It is also useful as a primer or intermediate coating for moldings made of metals (steel sheets, surface-treated steel sheets, etc.), plastics, wood, films, inorganic materials, and the like. It is also useful as a paint for imparting cosmetic properties, weather resistance, acid resistance, rust resistance, chipping resistance, etc. to pre-coated metals including rust-proof steel sheets, automobile paints, and the like. It is also useful as a urethane raw material for adhesives, adhesives, elastomers, foams, surface treatment agents and the like.

≪Paint film≫
The coating film of this embodiment is obtained by curing the coating composition.
Since the coating film of the present embodiment is formed by curing the coating composition, it always exhibits stable quality, and is less prone to popping and whitening even under high humidity curing conditions, and has excellent appearance. .

<Method for producing coating film>
The method for producing a coating film of the present embodiment is a method including the step of curing the coating composition.

The coating film of the present embodiment is obtained by coating the above coating composition on a molded article using a known coating method such as roll coating, curtain flow coating, spray coating, bell coating, and electrostatic coating, and then curing. It can be manufactured by
Examples of the molded article include those similar to the molded article obtained by molding the material exemplified in the above "<Usage of use of the coating composition>".

≪Coverage≫
The coating of the present embodiment includes a molded article and the coating film coated on the surface of the molded article.
Since the coated article of the present embodiment has the above coating film, it always exhibits stable quality and is excellent in appearance.

<Manufacturing method of coating>
The coated article of the present embodiment is obtained by coating the surface of the molded article with the coating film.
Specifically, the method for producing a coating of the present embodiment is a method including the steps of applying the coating composition to the surface of a molded article and curing the coating composition.

Examples of the coating method of the coating composition include the same methods as exemplified in the above "<Method for producing coating film>".
Examples of the molded article include those similar to the molded article obtained by molding the material exemplified in the above "<Usage of use of the coating composition>".
The shape of the molded article is not particularly limited. For example, it may be a thin one such as a film, a sheet, or a board, or a thick one such as a cylinder or a three-dimensional structure. Alternatively, it may be hollow such as a tube.

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

<Method for measuring physical properties>
[Physical Property 1] Viscosity The viscosity of the polyisocyanate composition was measured at 25° C. using an E-type viscometer (manufactured by Tokimec). A standard rotor (1°34′×R24) was used for the measurement. The number of revolutions is as follows.

(Number of revolutions)
100r. p. m. (When less than 128 mPa s)
50r. p. m. (In the case of 128 mPa s or more and less than 256 mPa s)
20r. p. m. (In the case of 256 mPa·s or more and less than 640 mPa·s)
10r. p. m. (640 mPa·s or more and less than 1280 mPa·s)
5r. p. m. (In the case of 1280 mPa s or more and less than 2560 mPa s)
2.5r. p. m. (In the case of 2560 mPa s or more and less than 5120 mPa s)
1.0r. p. m. (In the case of 5120 mPa s or more and less than 12800 mPa s)
0.5r. p. m. (In the case of 12800 mPa s or more and less than 25600 mPa s)

25600mPa. Viscosities exceeding s were measured using a rheometer (RS-1 manufactured by HAAKE). A rotor of 2°×R10 was used.

[Physical property 2] Non-volatile content When the polyisocyanate compositions produced in Examples and Comparative Examples are used as samples and diluted with a solvent, the mass of an aluminum cup is precisely weighed, about 1 g of the sample is placed, and the sample is heated and dried. was accurately weighed. The cup containing the above sample was heated in a dryer at 105°C for 3 hours. After cooling the heated cup to room temperature, the mass of the cup was accurately weighed again. The mass % of the dry residue in the sample was defined as the non-volatile content. The method for calculating the non-volatile content is as follows. In the case of no solvent dilution, the non-volatile content was treated as substantially 100%.

Non-volatile content (mass%) = (Cup weight after heat drying - Aluminum cup weight) / (Cup weight before heat drying - Aluminum cup weight) x 100%

[Physical property 3] Isocyanate group content (NCO%)
The isocyanate group content (% by mass) was obtained by neutralizing the isocyanate groups in the polyisocyanate composition with an excess of 2N amine, followed by back titration with 1N hydrochloric acid. The non-volatile content of the polyisocyanate composition was examined by the method described above, and those with a value of 98% by mass or more were measured as they were. In addition, when the content was less than 98% by mass, a refining device such as a thin film evaporator was used to increase the non-volatile content to 98% by mass or more, and then the NCO% was measured.
In the case of a blocked polyisocyanate composition, the NCO% was measured after dissociating the blocking agent by heating to about 120° C. or higher and 150° C. or lower under reduced pressure in a flask or the like while stirring, or passing through a thin film evaporator. . Also, the NCO % in the block polyisocyanate composition is referred to as latent NCO content.

[Physical property 4] Number average molecular weight and isocyanurate trimer content The number average molecular weight and isocyanurate trimer content of the measurement sample were measured by GPC. The measurement conditions of GPC are as follows.

(Measurement condition)
Equipment used: HLC-8120 (manufactured by Tosoh Corporation)
Columns used: TSK GEL SuperH1000, TSK GEL SuperH2000, TSK GEL SuperH3000 (all manufactured by Tosoh Corporation)
Sample concentration: 5 wt/vol% (50 mg of sample was dissolved in 1 mL of tetrahydrofuran (THF))
Carrier: THF
Detection method: Parallax refractometer Outflow rate: 0.6 mL/min Column temperature: 30°C

Polystyrene having a molecular weight of 1,000 to 20,000 and isocyanurate multimers (trimer, pentamer, heptamer) of 1,6-diisocyanatohexane were used to prepare the calibration curve. The isocyanurate trimer content was obtained from the ratio of the area of the peak with a molecular weight of about 500.

The non-volatile content of the polyisocyanate compositions produced in Examples and Comparative Examples was examined by the method described above, and those with a value of 98% by mass or more were measured as they were. In addition, when the content was less than 98% by mass, a refiner such as a thin film evaporator was used to increase the non-volatile content to 98% by mass or more, and then the number average molecular weight and the isocyanurate trimer content were measured.
In the case of a blocked polyisocyanate composition, in a flask or the like, while stirring, it is heated to about 120° C. or more and 150° C. or less under reduced pressure, or passed through a thin film evaporator to dissociate the blocking agent, and then the number average molecular weight and isocyanate Nurate trimer content was measured.

[Physical property 5] Average functional group number of isocyanate group (NCO average functional group number)
The average number of functional groups is the number of isocyanate functional groups statistically possessed by one polyisocyanate molecule, and was calculated using the following formula from the number average molecular weight (Mn) of polyisocyanate and the isocyanate group content (NCO%). .

Average functionality = Mn x NCO%/42

[Physical property 6] Content of structural units derived from polypropylene polyol and content of structural units derived from monoalcohol (Block) Content of structural units derived from polypropylene polyol and content of structural units derived from monoalcohol in polyisocyanate composition Amounts were calculated from the synthesis conditions.
In the case of a blocked polyisocyanate composition, in a flask or the like, while stirring, it is heated to about 120° C. or more and 150° C. or less under reduced pressure, or passed through a thin film evaporator to dissociate the blocking agent, and then the number average molecular weight and isocyanate Nurate trimer content was measured.

<Evaluation method>
[Evaluation 1] Appearance (foamability, whitening)
(1) Film Evaluation The polyisocyanate compositions produced in Examples and Comparative Examples are diluted with methoxypropyl acetate to a solid content of 80% by mass, and 3000 ppm of dibutyltin dilaurate is added to the polyisocyanate composition and stirred uniformly. Thus, a moisture-curable coating composition was obtained. Each of the obtained moisture-curable coating compositions was applied to a glass plate so as to have a film thickness of 100, 200, 400 or 600 μm, and cured under conditions of 23° C. and 50% RH. The appearance (foaming, whitening) of each film after 3 days from curing was confirmed and evaluated according to the evaluation criteria shown below.

(Evaluation criteria)
◎: No foaming or slightly foaming ○: Partial foamingf
△: Much foaming ×: Significant foaming, surface skinning or significant whitening

(2) Evaluation of coating film 1
The polyisocyanate compositions produced in Examples and Comparative Examples were mixed with Setarax 1767 (manufactured by Ornex Japan Co., Ltd., acrylic polyol) at NCO/OH = 2/1, and diluted with propyl methoxy acetate to a solid content of 50% by mass. and uniformly mixed to obtain each coating composition. Each coating composition thus obtained was applied to a glass plate so as to have a film thickness of 200 μm, and cured under conditions of 23° C. and 50% RH. The appearance (foaming, whitening) of each coating film three days after curing was confirmed and evaluated according to the evaluation criteria shown in (1) above.

(3) Evaluation of coating film 2
The blocked polyisocyanate compositions produced in Examples and Comparative Examples were mixed with Setarax 1767 at an NCO/OH ratio of 3/1, diluted with propylmethoxyacetate to a solid content of 50% by mass, and uniformly mixed to obtain each A coating composition was obtained. Each coating composition obtained was applied to a glass plate so as to have a film thickness of 100 μm, baked at 120° C. for 30 minutes, and then cured under saturated steam. The appearance (foaming, whitening) of each coating film three days after curing was confirmed and evaluated according to the evaluation criteria shown in (1) above.

<Production of polyisocyanate composition>
[Example 1] Production of polyisocyanate composition Pa1 and blocked polyisocyanate composition Ba1 (1) Production of polyisocyanate composition Pa1 HDI: 1000 g and polypropylene glycol having a molecular weight of 400: 33.8 g and n -Butanol: 5.9 g was subjected to a urethanization reaction at 80°C for 3 hours. 1.0 g of a tetramethylammonium decanoate solution containing 10% by mass of n-butanol was added and subjected to an isocyanurate reaction. When the NCO content of the reaction solution reached 36.9% by mass, diphosphate - n-butyl ester: 0.73 g was added to stop the reaction. Then, using a thin film evaporator, purification was performed twice under conditions of 160° C. and 0.03 kPa to obtain 490 g of polyisocyanate composition Pa1. The obtained polyisocyanate composition Pa1 has a viscosity of 4000 mPa·s (23° C.), a non-volatile content of 99.5% by mass, an NCO content of 19.6% by mass, a number average molecular weight of 770, and an NCO average functional group number of 3. 6. The isocyanurate trimer content is 45%, the content of structural units derived from polypropylene glycol is 7.5% by mass, and the content of structural units derived from monoalcohol (n-butanol) is 1.3% by mass. rice field.

(2) Production of blocked polyisocyanate composition Ba1 To polyisocyanate composition A-1: 100 g, 3,5-dimethylpyrazole: 47.1 g and methoxypropyl acetate: 63.0 g were added, and the mixture was heated at 80°C for 2 hours. A block polyisocyanate composition Ba1 was obtained by reacting for a period of time. The resulting blocked polyisocyanate composition Ba1 had a non-volatile content of 70% by mass and a latent NCO content of 9.3% by mass.

[Example 2] Production of polyisocyanate composition Pa2 and blocked polyisocyanate composition Ba2 (1) Production of polyisocyanate composition Pa2 1000 g of HDI and 30 g of polypropylene triol having a molecular weight of 1000 were heated at 80°C. for 3 hours. 9 g of a tetramethylammonium capriate solution containing 1% by mass of 2-ethylhexanol was added to cause an isocyanurate reaction. When the NCO content of the reaction solution reached 40.7% by mass, di-n phosphate was added. -Butyl ester: 0.63 g was added to stop the reaction. Then, using a thin film evaporator, purification was performed twice under conditions of 160° C. and 0.03 kPa to obtain 350 g of polyisocyanate composition Pa2. The obtained polyisocyanate composition Pa2 has a non-volatile content of 99.5% by mass, a viscosity of 1500 mPa·s (23°C), an NCO content of 20.2% by mass, a number average molecular weight of 710, and an NCO average functional group number of 3. 4. The isocyanurate trimer content is 49%, the content of structural units derived from polypropylene triol is 9.6% by mass, and the content of structural units derived from monoalcohol (2-ethylhexanol) is 2.7% by mass. there were.

(2) Production of blocked polyisocyanate composition Ba2 To polyisocyanate composition A-1: 100 g, 3,5-dimethylpyrazole: 50.9 g and methoxypropyl acetate: 37.7 g were added, and 2 A block polyisocyanate composition Ba2 was obtained by reacting for a period of time. The resulting blocked polyisocyanate composition Ba2 had a non-volatile content of 80% by mass and a latent NCO content of 10.7% by mass.

[Example 3] Production of polyisocyanate composition Pa3 and blocked polyisocyanate composition Ba3 (1) Production of polyisocyanate composition Pa3 HDI: 1000 g was heated to 70°C, and 2-ethylhexanol 11.0 g of a tetramethylammonium decanoate solution containing 1.0% by mass of is added to cause an isocyanurate reaction, and when the NCO content of the reaction solution reaches 39.8% by mass, 85% aqueous phosphoric acid was added to stop the reaction. Then, using a thin film evaporator, purification was performed twice under conditions of 160° C. and 0.03 kPa to obtain 370 g of polyisocyanate composition Pa0. The obtained polyisocyanate composition Pa0 has a nonvolatile content of 99.5% by mass, a viscosity of 2700 mPa s (23° C.), an NCO content of 21.8% by mass, a number average molecular weight of 630, and an NCO average functional group number of 3.3. , the isocyanurate trimer content was 40%, and the content of structural units derived from monoalcohol (2-ethylhexanol) was 3.0% by mass.
Next, 15.3 g of polypropylene glycol having a molecular weight of 400 was added to 182.8 g of polyisocyanate composition Pa0, and the mixture was reacted at 120° C. for 2 hours to obtain polyisocyanate composition Pa3. The resulting polyisocyanate composition Pa3 has a non-volatile content of 99.4% by mass, an NCO content of 18.5% by mass, a viscosity of 11600 mPa s (23° C.), a number average molecular weight of 790, and an NCO average functional group number of 3.5. , The isocyanurate trimer content is 40%, the content of structural units derived from polypropylene glycol is 8.6% by mass, and the content of structural units derived from monoalcohol (2-ethylhexanol) is 3.0% by mass. rice field.

(2) Production of blocked polyisocyanate composition Ba3 To polyisocyanate composition Pa3: 100 g, 3,5-dimethylpyrazole: 44.5 g and methoxypropyl acetate: 48.2 g were added, and 2 A block polyisocyanate composition Ba3 was obtained by reacting for hours. The resulting blocked polyisocyanate composition Ba3 had a nonvolatile content of 75% by mass and a latent NCO content of 9.6% by mass.

[Example 4] Production of polyisocyanate composition Pa4 and blocked polyisocyanate composition Ba4 (1) Production of polyisocyanate composition Pa4 Using the same method as in Example 3 (1), A polyisocyanate composition Pa0 was obtained. Next, 18.69 g of polypropylene glycol having a molecular weight of 400 was added to 181.3 g of polyisocyanate composition Pa0, and the mixture was reacted at 120° C. for 2 hours to obtain polyisocyanate composition Pa4. The resulting polyisocyanate composition Pa4 has a nonvolatile content of 99.4% by mass, an NCO content of 17.8% by mass, a viscosity of 16700 mPa s (23° C.), a number average molecular weight of 830, and an NCO average functional group number of 3.5. , The isocyanurate trimer content is 35%, the content of structural units derived from polypropylene glycol is 10.8% by mass, and the content of structural units derived from monoalcohol (2-ethylhexanol) is 3.0% by mass. rice field.

(2) Production of blocked polyisocyanate composition Ba4 To polyisocyanate composition Pa4: 100 g, 3,5-dimethylpyrazole: 42.7 g and methoxypropyl acetate: 47.6 g were added, and After reacting for hours, a blocked polyisocyanate composition Ba4 was obtained. The resulting blocked polyisocyanate composition Ba4 had a nonvolatile content of 75% by mass and a latent NCO content of 9.3% by mass.

[Example 5] Production of polyisocyanate composition Pa5 and blocked polyisocyanate composition Ba5 (1) Production of polyisocyanate composition Pa5 Using the same method as in Example 3 (1), A polyisocyanate composition Pa0 was obtained. Next, 10 g of polypropylene glycol having a molecular weight of 600 was added to 190 g of polyisocyanate composition Pa0, and the mixture was reacted at 120° C. for 2 hours to obtain polyisocyanate composition Pa5. The resulting polyisocyanate composition Pa5 has a non-volatile content of 99.4% by mass, an NCO content of 20.0% by mass, a viscosity of 7500 mPa s (23° C.), a number average molecular weight of 700, and an NCO average functional group number of 3.3. , The isocyanurate trimer content is 45%, the content of structural units derived from polypropylene glycol is 5.4% by mass, and the content of structural units derived from monoalcohol (2-ethylhexanol) is 3.0% by mass. rice field.

(2) Production of blocked polyisocyanate composition Ba5 To polyisocyanate composition Pa5: 100 g, 3,5-dimethylpyrazole: 48.1 g and methoxypropyl acetate: 63.5 g were added, and After reacting for hours, a blocked polyisocyanate composition Ba5 was obtained. The resulting blocked polyisocyanate composition Ba5 had a nonvolatile content of 70% by mass and a latent NCO content of 9.5% by mass.

[Example 6] Production of polyisocyanate composition Pa6 and blocked polyisocyanate composition Ba6 (1) Production of polyisocyanate composition Pa6 Using the same method as in Example 3 (1), A polyisocyanate composition Pa0 was obtained. Next, 24 g of polypropylene glycol having a molecular weight of 600 was added to 176 g of polyisocyanate composition Pa0, and the mixture was reacted at 120° C. for 2 hours to obtain polyisocyanate composition Pa6. The resulting polyisocyanate composition Pa6 has a nonvolatile content of 99.6% by mass, an NCO content of 17.5% by mass, a viscosity of 17300 mPa s (23° C.), a number average molecular weight of 835, and an NCO average functional group number of 3.5. , The isocyanurate trimer content is 35%, the content of structural units derived from polypropylene glycol is 14.1% by mass, and the content of structural units derived from monoalcohol (2-ethylhexanol) is 3.0% by mass. rice field.

(2) Production of blocked polyisocyanate composition Ba6 To polyisocyanate composition Pa6: 100 g, 3,5-dimethylpyrazole: 42.1 g and methoxypropyl acetate: 60.9 g were added, and 2 A block polyisocyanate composition Ba6 was obtained by reacting for hours. The resulting blocked polyisocyanate composition Ba6 had a non-volatile content of 70% by mass and a latent NCO content of 8.6% by mass.

[Example 7] Production of polyisocyanate composition Pa7 and blocked polyisocyanate composition Ba7 (1) Production of polyisocyanate composition Pa7 Using the same method as in Example 3 (1), A polyisocyanate composition Pa0 was obtained. Next, 25 g of polypropylene glycol having a molecular weight of 300 was added to 175 g of polyisocyanate composition Pa0, and the mixture was reacted at 120° C. for 2 hours to obtain polyisocyanate composition Pa7. The resulting polyisocyanate composition Pa7 has a non-volatile content of 99.5% by mass, an NCO content of 15.6% by mass, a viscosity of 25600 mPa s (23° C.), a number average molecular weight of 1030, and an average number of NCO functional groups of 3.8. , The isocyanurate trimer content is 32%, the content of structural units derived from polypropylene glycol is 14.7% by mass, and the content of structural units derived from monoalcohol (2-ethylhexanol) is 4.0% by mass. rice field.

(2) Production of blocked polyisocyanate composition Ba7 To polyisocyanate composition Pa7: 100 g, 3,5-dimethylpyrazole: 37.4 g and methoxypropyl acetate: 58.9 g were added, and the mixture was heated at 80°C for 2 hours. A block polyisocyanate composition Ba7 was obtained by reaction. The resulting blocked polyisocyanate composition Ba7 had a nonvolatile content of 70% by mass and a latent NCO content of 7.9% by mass.

[Example 8] Production of polyisocyanate composition Pa8 and blocked polyisocyanate composition Ba8 (1) Production of polyisocyanate composition Pa8 Using the same method as in Example 3 (1), A polyisocyanate composition Pa0 was obtained. Next, polyisocyanate composition Pa0: 190 g, polypropylene glycol having a molecular weight of 300: 10 g and 2-ethylhexanol: 3.5 g were added and reacted at 120 ° C. for 2 hours to obtain polyisocyanate composition Pa8. Obtained. The resulting polyisocyanate composition Pa8 has a nonvolatile content of 99.3% by mass, an NCO content of 18.4% by mass, a viscosity of 6000 mPa s (23° C.), a number average molecular weight of 760, and an NCO average functionality of 3.2. , The isocyanurate trimer content is 40%, the content of structural units derived from polypropylene glycol is 5.4% by mass, and the content of structural units derived from monoalcohol (2-ethylhexanol) is 4.9% by mass. rice field.

(2) Production of blocked polyisocyanate composition Ba8 To polyisocyanate composition Pa8: 100 g, 3,5-dimethylpyrazole: 44.3 g and methoxypropyl acetate: 61.8 g were added, and 2 A block polyisocyanate composition Ba8 was obtained by reacting for hours. The resulting blocked polyisocyanate composition Ba8 had a non-volatile content of 70% by mass and a latent NCO content of 8.9% by mass.

[Comparative Example 1] Production of polyisocyanate composition P-b1 and blocked polyisocyanate composition B-b1 (1) Production of polyisocyanate composition P-b1 Using the same method as in Example 3 (1), A polyisocyanate composition Pa0 was obtained. This polyisocyanate composition Pa0 was designated as polyisocyanate composition P-b1. The obtained polyisocyanate composition P-b1 has a nonvolatile content of 99.5% by mass, a viscosity of 2700 mPa s (23° C.), an NCO content of 21.8% by mass, a number average molecular weight of 630, and an NCO average functional group number of 3.3. , the isocyanurate trimer content was 32%, and the content of structural units derived from monoalcohol (2-ethylhexanol) was 3.0% by mass.

(2) Production of blocked polyisocyanate composition B-b1 To polyisocyanate composition P-b1: 100 g, 3,5-dimethylpyrazole: 52.4 g and methoxypropyl acetate: 65.3 g were added, and the mixture was heated at 80°C for 2 hours. After reacting for hours, a blocked polyisocyanate composition B-b1 was obtained. The resulting blocked polyisocyanate composition B-b1 had a nonvolatile content of 70% by mass and a latent NCO content of 10.0% by mass.

[Comparative Example 2] Production of polyisocyanate composition P-b2 and blocked polyisocyanate composition B-b2 (1) Production of polyisocyanate composition P-b2 Using the same method as in Example 3 (1), A polyisocyanate composition Pa0 was obtained. Next, 35 g of polypropylene glycol having a molecular weight of 300 was added to 165 g of polyisocyanate composition Pa0, and the mixture was reacted at 120° C. for 2 hours to obtain polyisocyanate composition P-b2. Polyisocyanate composition P-b2 has a nonvolatile content of 99.4% by mass, an NCO content of 13.1% by mass, a viscosity of 38500 mPa s (23° C.), a number average molecular weight of 1380, an NCO average functionality of 4.3, and an isocyanurate. The trimer content was 32%, the content of structural units derived from polypropylene glycol was 21.9% by mass, and the content of structural units derived from monoalcohol (2-ethylhexanol) was 4.9% by mass.

(2) Production of blocked polyisocyanate composition B-b2 To polyisocyanate composition P-b2: 100 g, 3,5-dimethylpyrazole: 31.5 g and methoxypropyl acetate: 56.3 g were added and After reacting for hours, a blocked polyisocyanate composition B-b2 was obtained. The resulting blocked polyisocyanate composition B-b2 had a nonvolatile content of 70% by mass and a latent NCO content of 7.0% by mass.

[Comparative Example 3] Production of polyisocyanate composition P-b3 and blocked polyisocyanate composition B-b3 (1) Production of polyisocyanate composition P-b3 Using the same method as in Example 3 (1), A polyisocyanate composition Pa0 was obtained. Next, 5 g of polypropylene glycol having a molecular weight of 1500 was added to 195 g of polyisocyanate composition Pa0, and the mixture was reacted at 120° C. for 2 hours to obtain polyisocyanate composition P-b3. Polyisocyanate composition P-b3 has a non-volatile content of 99.8% by mass, an NCO content of 21.1% by mass and a viscosity of 4000 mPa.s. s (23 ° C.), number average molecular weight 650, NCO average functional group number 3.3, isocyanurate trimer content 52%, content of structural units derived from polypropylene glycol 2.6% by mass, monoalcohol (2- The content of structural units derived from ethylhexanol) was 3.0% by mass.

(2) Production of blocked polyisocyanate composition B-b3 Polyisocyanate composition P-b3: 100 g was added with 3,5-dimethylpyrazole: 50.8 g and methoxypropyl acetate: 64.6 g, and the mixture was heated at 80°C for 2 hours. A blocked polyisocyanate composition B-b3 was obtained by reaction. The resulting blocked polyisocyanate composition B-b3 had a non-volatile content of 70% by mass and a latent NCO content of 9.8% by mass.

For the polyisocyanate compositions and blocked polyisocyanate compositions produced in Examples and Comparative Examples, films and coatings were produced and evaluated using the methods described above. Table 1 shows the results for the polyisocyanate composition, and Table 2 shows the results for the blocked polyisocyanate composition.

From Tables 1 and 2, in the films and coatings using the polyisocyanate compositions Pa1 to Pa8 and the blocked polyisocyanate compositions Ba1 to Ba8 obtained in Examples 1 to 8, any also had a good appearance.
In addition, in the films using the polyisocyanate compositions Pa1 to Pa8 obtained in Examples 1 to 8, the content of structural units derived from polypropylene polyol is 7.5% by mass or more and 10.8% by mass. Films using the following polyisocyanate compositions Pa1 to Pa4 (Examples 1 to 4) show less foaming and whitening as the thickness of the film increases, and have a particularly excellent appearance. rice field.

On the other hand, a polyisocyanate composition P-b1 (Comparative Example 1) containing no structural units derived from polypropylene polyol, and a polyisocyanate composition P-b2 having a content of structural units derived from polypropylene polyol of 15% by mass or more. In the film using (Comparative Example 2) or the polyisocyanate composition P-b3 (Comparative Example 3) having an isocyanurate trimer content of more than 50% by mass, the appearance deteriorated as the film thickness increased. , and significant bubbling and whitening were observed. Moreover, the coating films using the polyisocyanate compositions P-b1 to P-b3 and the blocked polyisocyanate compositions B-b1 to B-b3 obtained in Comparative Examples 1 to 3 had poor appearance.

According to the polyisocyanate composition of the present embodiment, a coating film excellent in appearance can be obtained even under high humidity curing conditions. The coating composition of the present embodiment is a primer, top intermediate coating, adhesive, adhesive, elastomer, foam, and surface treatment agent for molded articles formed by molding materials such as metals, plastics, wood, films, and inorganic materials. It is useful as a raw material for urethane such as

Claims (8)

A polyisocyanate composition having structural units derived from the following components (a) to (c) and having an isocyanurate group,
(a) 1,6-diisocyanatohexane;
(b) a polypropylene polyol;
(c) a monoalcohol;
The (a) trimer consisting of 3 molecules of 1,6-diisocyanatohexane and having an isocyanurate group has a content of 30% by mass or more and 50% by mass or less with respect to the total mass of the polyisocyanate composition,
The content of the structural unit derived from the (b) polypropylene polyol is 5% by mass or more and 15% by mass or less with respect to the mass of the structural unit derived from the (a) 1,6-diisocyanatohexane ,
The content of the (c) monoalcohol-derived structural unit is 1.0% by mass or more and 5.0% by mass or less with respect to the mass of the (a) 1,6-diisocyanatohexane-derived structural unit. can be,
The polyisocyanate composition , wherein the (c) monoalcohol has from 1 to 9 carbon atoms . 2. The polyisocyanate composition according to claim 1 , wherein the structural unit (b) derived from polypropylene polyol has a number average molecular weight of 300 or more and 1,000 or less. The polyisocyanate composition according to claim 1 or 2 , having an isocyanate group content of 15% by mass or more and 22% by mass or less. The polyisocyanate composition according to any one of claims 1 to 3 , wherein the isocyanate group has a functional group number of 3.0 or more and 4.5 or less. A blocked polyisocyanate composition comprising a part or all of the isocyanate groups of the polyisocyanate composition according to any one of claims 1 to 4 blocked with a pyrazole compound. A coating composition comprising the polyisocyanate composition according to any one of claims 1 to 4 or the blocked polyisocyanate composition according to claim 5 . A coating film obtained by curing the coating composition according to claim 6 . A coated article comprising a molded article and the coating film according to claim 7 coated on the surface of the molded article.