JP2016037539A - Polyisocyanate composition, paint composition and coating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyisocyanate composition that shows a small change in molecular weight after storage, and is resistant to yellow discoloration when baked at high temperatures.SOLUTION: A polyisocyanate composition according to the present invention comprises: a polyisocyanate obtained from an aliphatic diisocyanate unit comprising 1,6-diisocyanatohexane, and also having an isocyanurate group and a urethodione group; and 0.1-100 mass ppm of a phosphoric acid triester compound represented by the formula (I) (where R, R, Rmay be the same or different to represent a linear, branched or cyclic C1-C20 alkyl group, or aryl group).SELECTED DRAWING: None

Description

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

  A polyisocyanate composition obtained from an aliphatic diisocyanate containing 1,6-diisocyanatohexane (hereinafter also referred to as HDI; hexamethylene diisocyanate) and containing an isocyanurate structure is excellent in weather resistance and heat resistance. Widely used.

  Further, in recent years, technological development for reducing the viscosity of a polyisocyanate used as a curing agent has been actively performed due to an increase in protection of the global environment (see, for example, Patent Document 1). It is because the usage-amount of the organic solvent used for a coating composition can be reduced by making polyisocyanate low viscosity. On the other hand, as one of techniques for reducing the viscosity of various polyisocyanates derived from aliphatic diisocyanates containing HDI and the like, there is a technique related to polyisocyanates having a low viscosity uretdione group (for example, see Patent Document 2).

  Furthermore, as an improvement in yellowing, a technique has also been proposed in which a polyisocyanate having a low yellowing degree can be obtained by adding a phosphite compound at the time of production (see, for example, Patent Document 3).

  In addition, a technology to improve stability in sealed containers and in moisture contact conditions by adding phosphorus compounds such as acidic phosphate compounds and acidic phosphate esters to polyisocyanates containing isocyanurate groups has also been proposed. (For example, see Patent Document 4).

JP 05-222007 A Japanese Patent No. 3055197 JP 63-96178 A JP 2004-175888 A

  However, since the polyisocyanate described in Patent Documents 1 and 2 has a uretdione group that is inferior in heat resistance, the molecular weight changes after storage depending on storage conditions, and is used as a curing agent for paints. When it is baked at high temperature, it may turn yellow.

  Patent Documents 3 and 4 are intended to prevent yellowing and stabilize isocyanurate-type polyisocyanates, respectively, and relate to low-viscosity polyisocyanate compositions containing uretdione groups. No investigation has been made on molecular weight change and yellowing during high temperature baking.

  Therefore, an object of the present invention is to provide a polyisocyanate containing an isocyanurate group and a uretdione group, which has a small change in molecular weight after storage and a small yellowing property at high temperature baking.

  As a result of diligent research, the present inventors have added a specific amount of a specific phosphate triester compound to a polyisocyanate obtained from an aliphatic diisocyanate unit containing at least HDI and having an isocyanurate group and a uretdione group. It discovered that the polyisocyanate composition which was able to achieve the said subject and came to complete this invention.

（式中、Ｒ₁、Ｒ₂、Ｒ₃は、同じでも異なっていてもよく、直鎖状、分岐状若しくは環状の炭素数１〜２０のアルキル基、又はアリール基を表す。）
［２］
［１］に記載のポリイソシアネート組成物と、
水酸基価が１０〜２００ｍｇＫＯＨ／ｇであるアクリルポリオール及び／又は水酸基価が１０〜２００ｍｇＫＯＨ／ｇであるポリエステルポリオールと、
を含む、塗料組成物。
［３］
［２］に記載の塗料組成物を硬化させることにより得られる、塗膜。 That is, the present invention is as follows.
[1]
A polyisocyanate obtained from an aliphatic diisocyanate unit containing 1,6-diisocyanatohexane and having an isocyanurate group and a uretdione group;
0.1 to 100 ppm by mass of a phosphoric acid triester compound represented by the following formula (I):
Containing a polyisocyanate composition.

(In formula, R < ₁ >, R < ₂ >, R < ₃ > may be the same or different, and represents a linear, branched or cyclic C1-C20 alkyl group or an aryl group.)
[2]
The polyisocyanate composition according to [1],
An acrylic polyol having a hydroxyl value of 10 to 200 mgKOH / g and / or a polyester polyol having a hydroxyl value of 10 to 200 mgKOH / g;
A coating composition comprising:
[3]
A coating film obtained by curing the coating composition according to [2].

  According to the present invention, it is possible to provide a polyisocyanate composition having a small change in molecular weight after storage and a small yellowing property at high temperature baking.

  Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as “the present embodiment”) will be described 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 implemented with appropriate modifications within the scope of the gist. Unless otherwise specified, “(meth) acryl” includes methacryl and acryl, and “(meth) acrylate” includes methacrylate and acrylate.

  The polyisocyanate composition of the present embodiment is obtained from an aliphatic diisocyanate unit containing at least HDI, and has a polyisocyanate having an isocyanurate group and a uretdione group, and a phosphate triester compound represented by the following formula (I) 0.1-100 mass ppm. Since the polyisocyanate composition of the present embodiment is configured as described above, the molecular weight change after storage is small, and yellowing is small during baking at high temperature.

（式中、Ｒ₁、Ｒ₂、Ｒ₃は、同じでも異なっていてもよく、直鎖状、分岐状若しくは環状の炭素数１〜２０個のアルキル基、又はアリール基を表す。）

(In formula, R < ₁ >, R < ₂ >, R < ₃ > may be same or different, and represents a linear, branched or cyclic C1-C20 alkyl group or an aryl group.)

  Although it does not specifically limit as aliphatic diisocyanate, A C4-C30 thing is preferable, For example, in addition to HDI, 1, 4- diisocyanato butane, 1, 5- diisocyanato pentane, 2, 2, Examples include 4-trimethyl-1,6-diisocyanatohexane and lysine diisocyanate. Among these, from the viewpoint of industrial availability and reactivity during production of the polyisocyanate, polyisocyanate obtained from an aliphatic diisocyanate unit containing HDI is used in the present embodiment. Aliphatic diisocyanates may be used alone or in combination of two or more.

  The polyisocyanate composition of this embodiment may contain a part of alicyclic diisocyanate. Although it does not specifically limit as alicyclic diisocyanate, A C8-C30 thing is preferable, Isophorone diisocyanate (henceforth IPDI), 1, 3-bis (isocyanatomethyl) -cyclohexane, 4,4 ' -Dicyclohexylmethane diisocyanate, norbornene diisocyanate, hydrogenated xylylene diisocyanate and the like are exemplified. Among these, IPDI is preferable from the viewpoint of weather resistance and industrial availability. An alicyclic diisocyanate may be used independently and may use 2 or more types together.

  The isocyanurate group, which is one of the constituent components of the polyisocyanate composition of the present embodiment, is a polyisocyanate-derived functional group composed of three molecules of a diisocyanate monomer, and is represented by the following formula (II).

  Although the density | concentration of the isocyanurate trimer in the polyisocyanate composition of this embodiment is not specifically limited, It is preferable that it is 55-95 mass%, More preferably, it is 60-95 mass%. From the viewpoint of reducing the viscosity of the polyisocyanate composition, it is preferably 55% by mass or more, and from the viewpoint of keeping the yield of the polyisocyanate composition high, it is preferably 95% by mass or less. The concentration can be determined by measurement by gel permeation chromatography (hereinafter also referred to as GPC).

  The uretdione group, which is one of the components of the polyisocyanate composition of the present embodiment, is a polyisocyanate-derived functional group composed of two molecules of a diisocyanate monomer, and is represented by the following formula (III).

The molar ratio of uretdione group / isocyanurate group is not particularly limited, but is preferably 0.01 to 0.50. The lower limit value of the molar ratio is more preferably 0.02, still more preferably 0.03, and still more preferably 0.05. The upper limit of the molar ratio is more preferably 0.45, still more preferably 0.40, and still more preferably 0.35. From the viewpoint of reducing the viscosity of the polyisocyanate composition, it is preferably 0.01 or more, and from the viewpoint of improving crosslinkability, it is preferably 0.50 or less. The molar ratio can be determined by ¹³ C-NMR measurement. Specifically, it can measure according to the method as described in an Example.

  Moreover, the polyisocyanate composition of this embodiment may contain an allophanate group. The allophanate group is formed from a hydroxyl group of an alcohol and an isocyanate group, and is represented by the following formula (IV).

  The alcohol that can be used in the polyisocyanate composition of the present embodiment is preferably an alcohol formed only of carbon, hydrogen, and oxygen, and more preferably a monoalcohol. A molecular weight of 200 or less is particularly preferable. Specific examples of the compound include, but are not limited to, monoalcohols such as methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, and nonanol, ethylene glycol, 1,3-butanediol, and neopentyl. There are dialcohols such as glycol and 2-ethylhexanediol, and two or more of them may be used in combination.

The molar ratio of allophanate group / isocyanurate group derived from alcohol is preferably 0.01 to 0.20, more preferably 0.01 to 0.10, still more preferably 0.01 to 0.05. It is. From the viewpoint of improving the crosslinkability, it is preferably 0.20 or less. The molar ratio can be determined by ¹³ C-NMR measurement. Specifically, according to the method described in the Examples, it can be measured using the integrated value of the signal around 148.6 ppm (isocyanurate) and around 154 ppm (allophanate).

  In addition to the above, the polyisocyanate composition of the present embodiment may contain a urethane group, a urea group, a burette group, a carbodiimide group, and the like.

  The diisocyanate monomer concentration in the polyisocyanate composition of the present embodiment is preferably 1% by mass or less, more preferably 0.5% by mass or less, still more preferably 0.3% by mass, and still more preferably 0.8%. 2% by mass. From the viewpoint of improving the crosslinkability, the content is preferably 1% by mass or less. The said density | concentration can be calculated | required by the measurement of a gas chromatography.

  Although the viscosity in 25 degreeC of the polyisocyanate composition of this embodiment is not specifically limited, It is preferable that it is 100-1500 mPa * s. As a lower limit, it is more preferable that it is 150 mPa * s, More preferably, it is 200 mPa * s. The upper limit is more preferably 1000 mPa · s, still more preferably 800 mPa · s, and still more preferably 700 mPa · s. From the viewpoint of improving the crosslinkability, it is preferably 100 mPa · s or more, and from the viewpoint of increasing the solid content concentration of the coating material using the polyisocyanate composition, it is preferably 1500 mPa · s or more. The viscosity can be measured by using an E-type viscometer (manufactured by Tokimec).

  The content of isocyanate groups (NCO content) in the polyisocyanate composition of the present embodiment is preferably 21 to 25% by mass. The lower limit is more preferably 22% by mass, and the upper limit is more preferably 24% by mass. From the viewpoint of improving the coating film properties such as coating film hardness, it is preferably 21% by mass or more, and from the viewpoint of reducing the diisocyanate monomer concentration, it is preferably 25% by mass or less. The NCO content can be obtained by back titration with 1N hydrochloric acid after neutralizing the isocyanate group of the polyisocyanate composition with an excess of 2N amine. In addition, NCO content rate is a value with respect to solid content of a polyisocyanate composition, and solid content of a polyisocyanate composition can be measured according to the method as described in the Example mentioned later.

  The number average molecular weight of the solid content in the polyisocyanate composition of the present embodiment is not particularly limited, but is preferably 400 to 1,000. The lower limit of the number average molecular weight is more preferably 440, still more preferably 480. The upper limit of the number average molecular weight is more preferably 800, still more preferably 700, and still more preferably 600. By setting the number average molecular weight to 400 or more, the yield of the resulting polyisocyanate composition tends to be further improved. By setting the number average molecular weight to 1,000 or less, the gloss of the resulting coating film tends to be further improved. The number average molecular weight can be determined by GPC. Specifically, it can measure according to the method as described in an Example.

  The polyisocyanate composition of the present embodiment contains 0.1 to 100 ppm by mass of the phosphoric acid triester compound represented by the above formula (I) from the viewpoint of molecular weight change reduction after storage and yellowing reduction at high temperature baking. contains. The lower limit of the content of the phosphate triester compound is more preferably 1 ppm, more preferably, from the viewpoint of better expressing the change in chromaticity during storage, the change in viscosity and molecular weight during storage. 3 ppm, more preferably 5 ppm, and even more preferably 10 ppm. Further, the upper limit of the content of the phosphate triester compound is more preferably 80 ppm, more preferably 65 ppm, and still more preferably 50 ppm, from the viewpoint of improving moisture stability. More preferably, it is 35 ppm or less. The concentration of the phosphate triester compound can be determined by GC / MS (gas chromatography mass spectrometry) measurement. Specifically, it can measure according to the method as described in an Example.

  The phosphoric triester compound will be specifically described below.

Specific examples of R ₁ , R ₂ and R ₃ in formula (I) include, but are not limited to, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, n-pentyl. Group, n-hexyl group, cyclohexyl group, 2-ethylhexyl group, phenyl group, cresyl group, xylyl group, ethylphenyl group, isopropylphenyl group, benzyl group and the like. The upper limit value of the carbon number of R ₁ , R ₂ , and R ₃ is more preferably 15 from the viewpoint of reduction in chromaticity change after storage, reduction in change in viscosity and molecular weight, further preferably 10, Preferably it is 5, and even more preferably, it is 3.

  The phosphate ester compound is not particularly limited as long as it is a triester compound of phosphoric acid and an alcohol compound or a phenol compound. The aliphatic phosphate triester, the alicyclic phosphate triester, the aromatic phosphate triester, and the fat Any of group-aromatic phosphoric acid triesters may be used.

  Specific examples of aliphatic phosphate triesters include, but are not limited to, trimethyl phosphate, triethyl phosphate, tri (n-propyl) phosphate, triisopropyl phosphate, tri (n-butyl) phosphate, phosphorus Examples include triisobutyl acid, tri (n-pentyl) phosphate, tri (n-hexyl) phosphate, tri (2-ethylhexyl) phosphate and the like. Among them, trimethyl phosphate, triethyl phosphate, tri (n-propyl) phosphate, triisopropyl phosphate, tri (n-butyl phosphate) from the viewpoint of reducing chromaticity change, viscosity, and molecular weight change after storage. ), Triisobutyl phosphate, and tri (n-pentyl) phosphate, preferably trimethyl phosphate, triethyl phosphate, tri (n-propyl) phosphate, triphosphate One selected from isopropyl, tri (n-butyl) phosphate, and triisobutyl phosphate, and more preferably selected from trimethyl phosphate, triethyl phosphate, tri (n-propyl) phosphate, and triisopropyl phosphate. One type.

  Specific examples of the alicyclic phosphate triester include, but are not limited to, tricyclohexyl phosphate and the like.

  Specific examples of the aromatic phosphate triester include, but are not limited to, triphenyl phosphate, tricresyl phosphate, trixyl phosphate, cresyl phosphate (diphenyl), tri (isopropylphenyl) phosphate, and the like.

  Specific examples of the aliphatic-aromatic phosphate triester include, but are not limited to, methyl phosphate (diphenyl), dimethyl phosphate (phenyl), ethyl phosphate (diphenyl), diethyl phosphate (phenyl), and the like. Can be mentioned.

  Among these, aliphatic phosphate triesters and aliphatic-aromatic phosphate triesters are preferred, and aliphatic phosphate triesters are more preferred.

  Hereinafter, an example of the manufacturing method of the polyisocyanate composition of this embodiment is demonstrated.

  At least 1,6-diisocyanatohexane is used as a raw material for the polyisocyanate composition of the present embodiment. Furthermore, the polyisocyanate composition of the present embodiment performs an isocyanurate reaction for forming an isocyanurate group derived from an isocyanate group and an uretdione reaction for forming an uretdione group in the presence of an excess diisocyanate monomer. It can be obtained by removing the unreacted diisocyanate monomer.

  Furthermore, alcohol compounds such as alkyl monoalcohols and alkyl diols can be used in combination as auxiliary materials. Here, when using an alcohol compound, it is preferable to use it so that the molar ratio of the allophanate group / isocyanurate group in the polyisocyanate composition is in the range of 0.01 to 0.20.

  A polymerization catalyst is added to the raw material 1,6-diisocyanatohexane and the above-mentioned auxiliary materials, and the reaction is allowed to proceed until a predetermined degree of polymerization is reached. A polyisocyanate composition can be obtained by removing isocyanatohexane.

  When the isocyanurate group-containing polyisocyanate is derived from a diisocyanate monomer, an isocyanurate-forming catalyst is usually used. As a specific isocyanuration reaction catalyst, for example, a catalyst having basicity is generally preferable. Specific examples are shown below.

1) Tetraalkylammonium hydroxides such as tetramethylammonium and tetraethylammonium, and weak organic acid salts such as acetic acid and capric acid,
2) Hydroxyalkylammonium hydroxides such as trimethylhydroxypropylammonium, trimethylhydroxyethylammonium, triethylhydroxypropylammonium, triethylhydroxyethylammonium and the like, for example, organic weak acid salts with acetic acid, capric acid, etc. 3) Acetic acid, caproic acid, Metal salts of alkyl carboxylic acids such as octylic acid and myristic acid with, for example, tin, zinc, lead, sodium, potassium and the like 4) Metal alcoholates such as sodium and potassium 5) Aminosilyl group-containing compounds such as hexamethyldisilazane 6 ) Mannich bases 7) Combined use of tertiary amines and epoxy compounds. From the viewpoint of catalyst efficiency, the above 1), 2) and 3) are preferred. More preferably, it is an organic weak acid salt of 1).

  It is preferable to use these catalysts in an amount of 10 to 1000 ppm, more preferably 10 to 500 ppm, more preferably 10 to 100 ppm with respect to the charged diisocyanate mass, and the isocyanuration reaction temperature is 50 to 120 ° C. . The lower limit of the temperature is more preferably 60 ° C. Moreover, as an upper limit of temperature, it is more preferable that it is 100 degreeC, More preferably, it is 90 degreeC, More preferably, it is 80 degreeC. The isocyanurate reaction temperature is preferably 120 ° C. or lower from the viewpoint of preventing changes in properties such as coloring.

  The uretdione group present in the polyisocyanate composition of the present embodiment is obtained using a uretdione reaction catalyst. Examples of specific compounds of the uretdioneization reaction catalyst include, but are not limited to, trialkylphosphines such as tri-n-butylphosphine and tri-n-octylphosphine, which are tertiary phosphines, and tris- (dimethylamino). ) Tris (dialkylamino) phosphine such as phosphine, cycloalkylphosphine such as cyclohexyl-di-n-hexylphosphine, and the like. Many of these compounds simultaneously promote the isocyanuration reaction and produce isocyanurate group-containing polyisocyanates in addition to uretdione group-containing polyisocyanates. When the desired yield is obtained, a quenching agent for a uretdione reaction catalyst such as phosphoric acid or methyl paratoluenesulfonate is added to stop the uretdione reaction.

  Moreover, a uretdione group can also be obtained by heating the monomer of a diisocyanate, without using the above catalysts. The heating temperature is 120 ° C. to 180 ° C., and the lower limit is more preferably 130 ° C., further preferably 140 ° C., and further preferably 145 ° C. Further, the upper limit is more preferably 175 ° C., further preferably 170 ° C., and further preferably 165 ° C. The heating time is preferably 0.2 to 8 hours. As a lower limit, it is more preferable that it is 0.4Hr, More preferably, it is 0.7Hr, More preferably, it is 1.0Hr. As an upper limit, it is more preferable that it is 6Hr, More preferably, it is 4Hr, More preferably, it is 2Hr. By setting it to 0.2 Hr or more, there is a tendency that the viscosity can be further reduced, and by setting it to 8 Hr or less, there is a tendency that coloring of the polyisocyanate itself can be further suppressed.

  When the polyisocyanate composition of the present embodiment is obtained without using the uretdione reaction catalyst, after the uretdione reaction by heating alone and the above-mentioned isocyanurate reaction are completed, the unreacted diisocyanate monomer can be removed. It is preferable from the viewpoint of further reducing the unreacted diisocyanate monomer concentration, the effect of reducing the molecular weight change rate after storage of the obtained polyisocyanate composition, and the effect of reducing yellowing during high temperature baking.

  The above-described isocyanurate formation reaction and uretdione formation reaction can be performed sequentially, or some of them can be performed in parallel. Moreover, when accompanied by an allophanatization reaction, Preferably, an isocyanurate formation reaction and an allophanatization reaction are preceded in parallel, and a uretdioneization reaction is performed after that. More preferably, when the isocyanurate formation reaction and the allophanatization reaction are simultaneously performed using a common catalyst, and then the uretdione conversion reaction by heat is performed, the production process can be simplified, which is more preferable.

  When the polymerization reaction reaches a desired degree of polymerization, the polymerization reaction is stopped. The termination of the polymerization reaction is not limited to the following. For example, the polymerization reaction catalyst is neutralized by adding an acidic compound such as phosphoric acid, acidic phosphate ester, sulfuric acid, hydrochloric acid, sulfonic acid compound to the reaction solution, or This can be achieved by inactivation by thermal decomposition, chemical decomposition, or the like. After the reaction is stopped, if necessary, filtration is performed.

  Since the reaction liquid immediately after stopping the reaction usually contains unreacted HDI monomer, it is preferably removed by a thin film evaporator, extraction or the like. It is preferable to control the concentration of the HDI monomer contained in the polyisocyanate composition to 1% by mass or less by performing such post-treatment. The upper limit value of the HDI monomer concentration is more preferably 0.7% by mass or less, still more preferably 0.5% by mass or less, still more preferably 0.3% by mass or less, and still more preferably 0.8%. 2% by mass or less. By setting the HDI monomer concentration to the above upper limit or less, the toxicity of the polyisocyanate composition can be further reduced, and the safety tends to be further improved.

  The phosphate triester compound, which is an essential component of the polyisocyanate composition of the present embodiment, may be added before the reaction of the diisocyanate and the polyol compound, or may be added to the reaction liquid after the reaction is completed. Moreover, you may add to the polyisocyanate from which the HDI monomer was removed.

  The polyisocyanate composition of the present embodiment can also be suitably used as a curing agent for coating compositions. That is, the coating composition of this embodiment contains the polyisocyanate composition of this embodiment. Although it does not specifically limit as a resin component of the coating composition of this embodiment, It is preferable to contain the compound which has two or more active hydrogens which have reactivity with an isocyanate group in a molecule | numerator. Examples of the compound having two or more active hydrogens in the molecule include, but are not limited to, polyols, polyamines, polythiols and the like. Among these, a polyol is preferable. Specific examples of the polyol include, but are not limited to, polyester polyol, polyether polyol, acrylic polyol, polyolefin polyol, and fluorine polyol.

  The coating composition using the polyisocyanate composition of this embodiment can be used for both a solvent base and an aqueous base.

  In the case of a solvent-based coating composition, for example, 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 In addition to additives such as an agent, an antioxidant, an ultraviolet absorber, a light stabilizer, a plasticizer, and a surfactant, the polyisocyanate composition of the present embodiment is added as a curing agent, and if necessary, Further, after adding a solvent to adjust the viscosity, a solvent-based coating composition can be obtained by hand stirring or stirring using a stirring device such as Mazelar.

  In the case of a water-based coating composition, for example, an aqueous dispersion of a resin containing a compound having two or more active hydrogen atoms in the molecule, or an aqueous solution, and if necessary, other resins, catalysts, pigments The polyisocyanate composition of the present embodiment is added as a curing agent to those added with additives such as a leveling agent, an antioxidant, an ultraviolet absorber, a light stabilizer, a plasticizer, and a surfactant. Then, after further adding water or a solvent, a water-based coating composition can be obtained by forcibly stirring with a stirring device.

  Polyester polyol is not limited to the following, for example, dibasic carboxylic acid such as succinic acid, adipic acid, dimer acid, maleic anhydride, phthalic anhydride, isophthalic acid, terephthalic acid, 1,4-cyclohexanedicarboxylic acid, etc. An acid or the like alone or in combination with ethylene glycol, propylene glycol, diethylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, trimethylpentanediol, cyclohexanediol, trimethylolpropane, glycerin, pentaerythritol, It can be obtained by subjecting a polyhydric alcohol such as 2-methylolpropanediol or ethoxylated trimethylolpropane alone or a mixture to a condensation reaction. For example, the condensation reaction can be carried out by mixing the above components and heating at about 160-220 ° C. Furthermore, for example, polycaprolactones obtained by ring-opening polymerization of lactones such as ε-caprolactone using a polyhydric alcohol can also be used as the polyester polyol. These polyester polyols can be modified using aromatic diisocyanates, aliphatic diisocyanates, alicyclic diisocyanates, and polyisocyanates obtained therefrom. In this case, aliphatic diisocyanate, alicyclic diisocyanate, and polyisocyanate obtained from these are particularly preferable from the viewpoints of weather resistance, yellowing resistance, and the like. When used as an aqueous base paint, leave some carboxylic acid such as dibasic acid and neutralize it with a base such as amine or ammonia to make a water-soluble or water-dispersible resin. Can do.

  Examples of the polyether polyol include, but are not limited to, hydroxide (lithium, sodium, potassium, etc.), strong basic catalyst (alcolate, alkylamine, etc.), complex metal cyanide complex (metal porphyrin, hexacyanocobaltate) Polyether obtained by random or block addition of a single or mixture of alkylene oxide (ethylene oxide, propylene oxide, butylene oxide, cyclohexene oxide, styrene oxide, etc.) to a polyvalent hydroxy compound using a zinc complex etc. Polyols; polyether polyols obtained by reacting an alkylene oxide with a polyamine compound (ethylenediamine, etc.); and obtained by polymerizing acrylamide or the like using these polyether polyols as a medium. That polymers polyols and the like.

  Examples of the polyvalent hydroxy compound include, but are not limited to, (i), for example, diglycerin, ditrimethylolpropane, pentaerythritol, dipentaerythritol, etc. (ii), for example, erythritol, D-threitol, L-arabinitol, Sugar alcohol compounds such as ribitol, xylitol, sorbitol, mannitol, galactitol, rhamnitol, (iii) monosaccharides such as arabinose, ribose, xylose, glucose, mannose, galactose, fructose, sorbose, rhamnose, fucose, ribodesource, (Iv) For example, disaccharides such as trehalose, sucrose, maltose, cellobiose, gentiobiose, lactose, melibiose, (v), for example, raffinose, gentianose, mele Trisaccharides such as toast, (vi) e.g., tetrasaccharides such as stachyose, and the like.

  The acrylic polyol is not limited to the following, but is obtained, for example, by copolymerizing a polymerizable monomer having one or more active hydrogens in one molecule and another monomer copolymerizable with the polymerizable monomer. be able to.

  The acrylic polyol is not limited to the following, but, for example, acrylic acid esters having active hydrogen (such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate), or active hydrogen Methacrylic acid esters (methacrylic acid-2-hydroxyethyl, methacrylic acid-2-hydroxypropyl, methacrylic acid-2-hydroxybutyl, methacrylic acid-3-hydroxypropyl, methacrylic acid-4-hydroxybutyl, etc.), glycerin And (meth) acrylic acid esters having polyvalent active hydrogen such as (meth) acrylic acid monoesters of triols such as trimethylolpropane; polyether polyols (polyethylene glycol, polypropylene glycol, polybutylene glycol, etc.) Monoethers with (meth) acrylic acid esters having active hydrogen as described above; Adducts of glycidyl (meth) acrylate and monobasic acids such as acetic acid, propionic acid, p-tert-butylbenzoic acid; As an essential component, one or more selected from the group consisting of adducts obtained by ring-opening polymerization of lactones (ε-caprolactam, γ-valerolactone, etc.) with active hydrogen of (meth) acrylic acid esters having (Meth) acrylic acid esters (methyl acrylate, ethyl acrylate, isopropyl acrylate, acrylic acid-n-butyl, acrylate-2-ethylhexyl, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate) , Methacrylate-n-butyl, isobutyl methacrylate, methacrylic acid-n Hexyl, cyclohexyl methacrylate, lauryl methacrylate, glycidyl methacrylate, etc.), unsaturated carboxylic acids (acrylic acid, methacrylic acid, maleic acid, itaconic acid, etc.), unsaturated amides (acrylamide, N-methylol acrylamide, diacetone acrylamide) Etc.), or vinyl monomers having a hydrolyzable silyl group (vinyltrimethoxysilane, vinylmethyldimethoxysilane, γ- (meth) acrylopropyltrimethoxysilane, etc.), other polymerizable monomers (styrene, vinyltoluene, One or more selected from the group consisting of vinyl acetate, acrylonitrile, dibutyl fumarate, etc.) can be obtained by copolymerization by a conventional method.

  For example, an acrylic polyol can be obtained by solution polymerization of the above monomer components in the presence of a radical polymerization initiator such as a known peroxide or azo compound, and diluting with an organic solvent as necessary. Can do. In the case of obtaining an aqueous base acrylic polyol, it can be produced by a known method such as solution polymerization of an olefinically unsaturated compound and conversion to an aqueous layer or emulsion polymerization. In that case, water solubility or water dispersibility can be imparted by neutralizing an acidic moiety such as a carboxylic acid-containing monomer such as acrylic acid or methacrylic acid or a sulfonic acid-containing monomer with an amine or ammonia.

  Examples of the polyolefin polyol include, but are not limited to, polybutadiene having two or more hydroxyl groups, hydrogenated polybutadiene, polyisoprene, hydrogenated polyisoprene, and the like.

  Fluoropolyol is a polyol containing fluorine in the molecule, and is not limited to the following. For example, fluoroolefins and cycloolefins disclosed in JP-A-57-341075, JP-A-61-215311, etc. Examples thereof include copolymers such as vinyl ether, hydroxyalkyl vinyl ether, and monocarboxylic acid vinyl ester.

  Although the hydroxyl value of the said polyol is not specifically limited, It is preferable that it is 10-200 mgKOH / g. Among these, the lower limit is more preferably 20 mgKOH / g, and further preferably 30 mgKOH / g. The acid value of the polyol is preferably 0 to 30 mgKOH / g. The hydroxyl value and acid value can be measured according to JIS K1557.

  Among the above, as the polyol, an acrylic polyol is preferable from the viewpoint of weather resistance, chemical resistance, and hardness, and a polyester polyol is preferable from the viewpoint of mechanical strength and oil resistance. That is, the coating composition of the present embodiment includes the polyisocyanate composition of the present embodiment, an acrylic polyol having a hydroxyl value of 10 to 200 mgKOH / g and / or a polyester polyol having a hydroxyl value of 10 to 200 mgKOH / g, It is preferable to contain.

  The equivalent ratio (NCO / OH ratio) of the isocyanate group of the polyisocyanate composition of the present embodiment to the hydroxyl group of the compound having two or more active hydrogens in the molecule is preferably 0.2 to 5.0. More preferably, it is 0.4-3.0, More preferably, it is 0.5-2.0. When the equivalent ratio is 0.2 or more, a tougher coating film tends to be obtained. When the equivalent ratio is 5.0 or less, the smoothness of the coating film tends to be further improved.

  A melamine curing agent such as a complete alkyl type, a methylol type alkyl, or an imino group type alkyl can be added to the coating composition as necessary.

  Any of the compound having two or more active hydrogens in the molecule, the polyisocyanate composition of the present embodiment, and the coating composition of the present embodiment can be used by mixing with an organic solvent. Although it does not specifically limit as an organic solvent, It is preferable that it does not have a functional group which reacts with a hydroxyl group and an isocyanate group, and it is preferable that it is fully compatible with a polyisocyanate composition. Examples of such organic solvents include, but are not limited to, ester compounds, ether compounds, ketone compounds, aromatic compounds, ethylene glycol dialkyl ether compounds, and polyethylene glycol dicarboxylates that are generally used as coating solvents. Compounds, hydrocarbon solvents, aromatic solvents and the like.

  The compound having two or more active hydrogens in the molecule, the polyisocyanate composition of the present embodiment, and the coating composition of the present embodiment all have the desired effect of the present embodiment depending on the purpose and application. Use various additives used in the technical field such as catalysts, pigments, leveling agents, antioxidants, UV absorbers, light stabilizers, plasticizers, surfactants, etc. You can also.

  Examples of the curing accelerating catalyst include, but are not limited to, metal salts such as dibutyltin dilaurate, tin 2-ethylhexanoate, zinc 2-ethylhexanoate, and cobalt salt; triethylamine, pyridine, methylpyridine, And tertiary amines such as benzyldimethylamine, N, N-dimethylcyclohexylamine, N-methylpiperidine, pentamethyldiethylenetriamine, N, N′-endoethylenepiperazine, N, N′-dimethylpiperazine, and the like.

  Although the coating composition of this embodiment is not limited to the following, For example, it can be used as coating materials, such as roll coating, curtain flow coating, spray coating, bell coating, electrostatic coating. For example, it is useful as a primer or a top intermediate coating material for materials such as metals (steel plates, surface-treated steel plates, etc.), plastics, wood, films, inorganic materials and the like. Further, it is also useful as a paint for imparting cosmetic properties, weather resistance, acid resistance, rust resistance, chipping resistance, etc. to pre-coated metal containing rust-proof steel plates, automobile painting, and the like. Furthermore, it is also useful as a urethane raw material for adhesives, pressure-sensitive adhesives, elastomers, foams, surface treatment agents and the like.

  The coating film of this embodiment is obtained by curing the coating composition of this embodiment. Since it is comprised in this way, the coating film of this embodiment is a coating film which always expresses stable quality and has small yellowing even at the time of high-temperature baking.

  Although the film thickness of the coating film of this embodiment is not specifically limited, It is preferable that it is 5-200 micrometers. As a lower limit, it is more preferable that it is 10 micrometers, More preferably, it is 25 micrometers, More preferably, it is 30 micrometers. As an upper limit, it is more preferable that it is 150 micrometers, More preferably, it is 100 micrometers, More preferably, it is 75 micrometers.

  Moreover, the coating film of this embodiment may be a single layer film or a multilayer coating film of two or more layers with respect to the substrate.

  Hereinafter, although this embodiment is demonstrated in more detail based on an Example and a comparative example, this embodiment is not limited at all by the following examples.

<Viscosity>
The viscosity was measured at 25 ° C. using an E-type viscometer (manufactured by Tokimec). In the measurement, a standard rotor (1 ° 34 ′ × R24) was used. The number of rotations was as follows.
100 rpm (when less than 128 mPa · s)
50 rpm (in the case of 128 mPa · s to 256 mPa · s)
20 rpm (in the case of 256 mPa · s to 640 mPa · s)
10 rpm (from 640 mPa · s to 1280 mPa · s)
5 rpm (in the case of 1280 mPa · s to 2560 mPa · s)
In addition, the non-volatile content of the polyisocyanate composition produced in each Example and each Comparative Example described later was examined by the method described below, and those whose value was 98% by mass or more were subjected to various measurements as they were. .

<Nonvolatile content>
The nonvolatile content was determined from the remaining amount when the polyisocyanate composition was heated at 105 ° C. for 3 hours.
Nonvolatile content (mass%) = (mass of polyisocyanate composition after heating at 105 ° C. for 3 hours) / (mass of polyisocyanate composition before heating) × 100

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

<Number average molecular weight>
The number average molecular weight of the measurement sample was measured by GPC. The GPC measurement method was as follows.
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,
(Flow rate 0.6 mL / min, column temperature 30 ° C.).

  For the preparation of the calibration curve, polystyrene having a molecular weight of 1000 to 20000 and an isocyanurate of 1,6-diisocyanatohexane (trimer, pentamer, and heptamer) were used. In addition, the non volatile matter of the polyisocyanate composition produced by each Example and each comparative example mentioned later was investigated by the method mentioned above, and what was the value of 98 mass% or more was used for the measurement as it was. What was not so decided to use for a measurement by making the density | concentration of a non volatile matter 98 mass% or more using a thin film evaporator.

<Measurement of HDI monomer mass concentration>
First, a 20 mL sample bottle was placed on a digital balance, and about 1 g of the sample was precisely weighed. Next, 0.03 to 0.04 g of nitrobenzene (internal standard solution) was added and weighed accurately. Finally, after further adding about 9 mL of ethyl acetate, the lid was tightly mixed well to prepare a sample. The adjustment liquid was quantitatively analyzed by gas chromatography under the following conditions.
Apparatus: SHIMADZU Co., Ltd. GC-8A
Column: Shinwa Kako Co., Ltd. Silicone OV-17
Column oven temperature: 120 ° C
Injection / detector temperature; 160 ° C

<Mole ratio of uretdione group / isocyanurate group>
The molar ratio of uretdione group and isocyanurate group (Ud / Nu molar ratio) was determined by ¹³ C-NMR measurement using Biospin Avance 600 (trade name) manufactured by Bruker. Specific measurement conditions were as follows.
¹³ C-NMR apparatus: AVANCE 600 (manufactured by Bruker)
Cryoprobe (Bruker)
Cryo Probe
CPDUUL
600S3-C / HD-05Z
Resonance frequency: 150 MHz
Concentration: 60 wt / vol%
Shift standard: CDCl ₃ (77 ppm)
Integration count: 10,000 times Pulse program: zgpg30 (proton complete decoupling method, waiting time 2 sec)

The integral values of the following signals were divided by the number of carbons being measured, and each molar ratio was determined from the value.
Isocyanurate group: around 148.6 ppm: integral value ÷ 3
Uretodione group: Around 157.5 ppm: integral value / 2

<Qualitative and quantitative method of phosphoric acid triester compound in polyisocyanate composition>
First, a 20 mL sample bottle was placed on a digital balance, and about 2 g of the sample was precisely weighed. Next, after adding about 8 g of chloroform, the lid was tightly mixed well to prepare a sample. The adjustment liquid was qualitatively analyzed by GC / MS (gas chromatography mass spectrometry) measurement under the following conditions. Regarding the quantification of the phosphoric acid triester compound, the GC sensitivity of each phosphoric acid triester compound was regarded as the same as that of triethyl phosphate, and was quantified. The detection limit of this analysis was 0.05 ppm.

  A compound having a hydroxyl group on the phosphorus atom, such as a phosphoric acid diester compound, a phosphoric acid monoester compound, and a phosphoric acid compound, is qualitatively treated in the same manner as the phosphoric acid triester compound after trimethylsilylation treatment of the hydroxyl group. Quantification was performed.

GC device: Agilent Technologies 6890
Inlet temperature: 320 ° C
Injection volume: 1 μL
Injection method: split method (split ratio 10: 1)
Column: DB-1 (length 30 m, inner diameter 0.25 mm, liquid phase thickness 0.25 μm)
Column temperature: 40 ° C. (5 minutes hold) → 20 ° C./minute temperature rise → 320 ° C. (11 minutes hold)
MS equipment: Agilent Technologies 5973MSD
Ion source temperature: 230 ° C
Interface temperature: 300 ° C
Ionization method: Electron ionization method (EI)
Measurement method: SCAN method

<Molecular weight stability after storage>
The obtained polyisocyanate composition was added to a sample bottle and stored at 50 ° C. for 30 days. Based on the method described above, the molecular weight stability after storage was evaluated by measuring the number average molecular weight before and after storage. The case where the amount of change in the number average molecular weight before and after storage was 75 or more was evaluated as x, the case of 50 or more and less than 75 was evaluated as Δ, the case of 30 or more and less than 50 was evaluated as ○, and the case of less than 30 was evaluated as ３０.

<Evaluation of yellowing resistance of paint film during baking>
A solvent-based two-component urethane paint (polyol: acrylic polyol-based urethane; trade name “Mighty Lac (white)”, manufactured by Nippon Paint Co., Ltd.) was spray-coated on an aluminum plate to a thickness of 50 μm. Then, after leaving still at 23 degreeC and 50% humidity conditions for 2 weeks, the surface was grind | polished with the 1000th sandpaper, and the white board was produced.

  Next, the acrylic polyol Ac-1 obtained in Synthesis Example 1 below, the polyisocyanate composition obtained in each Example and Comparative Example, and the molar ratio of the NCO group of the polyisocyanate composition to the OH group of the acrylic polyol. (NCO / OH) is mixed at a ratio of 1.0, and “Solvesso # 100” (trade name, aromatic solvent manufactured by Exxon) is used to adjust the solid content to 55% by mass. A coating composition was prepared. Using a spray, the coating composition was applied to the white plate prepared above so that the dry film thickness was 40 μm. After baking this at 160 ° C. for 30 minutes, the yellow index (YI) was measured according to ASTM D1925 using a chromaticity system “SM-T45” (manufactured by Suga Test Instruments Co., Ltd.). Yellowing during baking was evaluated with a case where the YI of the coating after baking was less than 2.0, a case where the YI was 2.0 or more and less than 3.0, and a case where the YI was 3.0 or more.

(Synthesis Example 1; Synthesis of Acrylic Polyol Ac-1)
A four-necked flask equipped with a stirrer, a thermometer, and a condenser tube was charged with 120.0 g of “Solvesso # 150” (an aromatic solvent manufactured by Exxon Chemical) and 60.0 g of xylene, and the interior was purged with nitrogen The temperature was raised to 120 ° C. Thereafter, the following (meth) acrylic monomers (methyl methacrylate 128.8 g, n-butyl acrylate 84.8 g, cyclohexane methacrylate 80.0 g, 2-hydroxyethyl methacrylate 74.4 g, styrene 32.0 g) and benzoyl par Oxide 8.0g was dripped over 2 hours, and was made to react with stirring. After completion of the dropwise addition, the reaction was further continued at 120 ° C. for 4 hours to obtain acrylic polyol Ac-1.

  The obtained acrylic polyol Ac-1 had a nonvolatile content of 70% by mass, a hydroxyl value of 80 mgKOH / g, a glass transition temperature (Tg) of 40 ° C., and a number average molecular weight of 1700. In addition, the hydroxyl value was based on JIS K1557, and was made into the value calculated from the preparation ratio with respect to the resin part. The glass transition temperature was measured according to JIS K7121.

Example 1
A four-necked flask equipped with a stirrer, thermometer, reflux condenser, nitrogen blowing tube and dropping funnel was placed in a nitrogen atmosphere, charged with 6,000 g of HDI and 11 g of isobutanol, and the reactor temperature was 80 ° C. with stirring. Hold for 2 hours. Thereafter, 5.0 g of a solution obtained by diluting the isocyanuration catalyst trimethyl-2-methyl-2-hydroxyethylammonium hydroxide with isobutanol to 5% by mass is added to conduct an isocyanuration reaction, and the NCO content of the reaction solution is When it reached 45.5% by mass, phosphoric acid was added to stop the reaction. The uretdione dimer concentration increased by this reaction was 1% by mass or less. The reaction solution was further maintained at 160 ° C. for 1 hour. This heating produced uretdione group-containing polyisocyanate. Using a thin film evaporator, purified twice under the conditions of 160 ° C. and 0.2 Torr, non-volatile content 99.5% by mass, viscosity 260 mPa · s (25 ° C.), NCO content 23.2% by mass, HDI monomer concentration 0.13 mass% polyisocyanate p-1 was obtained. The molar ratio of uretdione group / isocyanurate group was 0.42.

  Thereafter, 15 mg of triisopropyl phosphate was added to 1,000 g of the obtained polyisocyanate p-1, and the mixture was stirred at 50 ° C. for 1 hour in a nitrogen atmosphere to obtain a polyisocyanate composition P-1. The resulting polyisocyanate composition P-1 has a viscosity of 260 mPa.s. S (25 degreeC), NCO content rate 23.2 mass%, number average molecular weight 510, content of triisopropyl phosphate was 15 ppm. In addition, molecular weight stability after storage and yellowing during high temperature baking were evaluated. The obtained results are shown in Table 1.

(Example 2)
A four-necked flask equipped with a stirrer, thermometer, reflux condenser, nitrogen blowing tube, and dropping funnel was placed in a nitrogen atmosphere, charged with 6,000 g of HDI and 7.0 g of isobutanol, and the reactor temperature was 80 with stirring. The temperature was maintained at 2 ° C. for 2 hours. Thereafter, 5.0 g of a solution obtained by diluting the isocyanuration catalyst trimethyl-2-methyl-2-hydroxyethylammonium hydroxide with isobutanol to 5% by mass is added to conduct an isocyanuration reaction, and the NCO content of the reaction solution is When the content reached 45.2% by mass, phosphoric acid was added to stop the reaction. The uretdione dimer concentration increased by this reaction was 1% by mass or less. The reaction solution was further maintained at 160 ° C. for 1 hour. This heating produced uretdione group-containing polyisocyanate. Using a thin film evaporator, purified twice at 160 ° C. and 0.2 Torr, non-volatile content 99.5% by mass, viscosity 400 mPa · s (25 ° C.), NCO content 23.2% by mass, HDI monomer concentration 0.11 mass% polyisocyanate p-2 was obtained. The molar ratio of uretdione group / isocyanurate group was 0.32.

  Thereafter, 20 mg of trimethyl phosphate was added to 1,000 g of the obtained polyisocyanate p-2, and the mixture was stirred at 50 ° C. for 1 hour in a nitrogen atmosphere to obtain a polyisocyanate composition P-2. The resulting polyisocyanate composition P-2 has a viscosity of 400 mPa.s. S (25 degreeC), NCO content rate 23.2 mass%, number average molecular weight 540, content of trimethyl phosphate was 20 ppm. In addition, molecular weight stability after storage and yellowing during high temperature baking were evaluated. The obtained results are shown in Table 1.

(Example 3)
20 mg of triethyl phosphate was added to 1,000 g of the polyisocyanate p-2 obtained in Example 2, and the mixture was stirred at 50 ° C. for 1 hour in a nitrogen atmosphere to obtain a polyisocyanate composition P-3. The resulting polyisocyanate composition P-3 had a viscosity of 400 mPa.s. S (25 degreeC), NCO content rate 23.2 mass%, number average molecular weight 540, content of triethyl phosphate was 20 ppm. In addition, molecular weight stability after storage and yellowing during high temperature baking were evaluated. The obtained results are shown in Table 1.

Example 4
2 mg of triethyl phosphate was added to 1,000 g of the polyisocyanate p-2 obtained in Example 2, and the mixture was stirred at 50 ° C. for 1 hour in a nitrogen atmosphere to obtain a polyisocyanate composition P-4. The resulting polyisocyanate composition P-4 has a viscosity of 400 mPa.s. S (25 degreeC), NCO content rate 23.2 mass%, number average molecular weight 540, and content of triethyl phosphate were 2 ppm. In addition, molecular weight stability after storage and yellowing during high temperature baking were evaluated. The obtained results are shown in Table 1.

(Example 5)
50 mg of triethyl phosphate was added to 1,000 g of the polyisocyanate p-2 obtained in Example 2, and the mixture was stirred at 50 ° C. for 1 hour in a nitrogen atmosphere to obtain a polyisocyanate composition P-5. The obtained polyisocyanate composition P-5 had a viscosity of 390 mPa.s. S (25 degreeC), NCO content rate 23.2 mass%, number average molecular weight 540, content of triethyl phosphate was 50 ppm. In addition, molecular weight stability after storage and yellowing during high temperature baking were evaluated. The obtained results are shown in Table 1.

(Example 6)
90 mg of triethyl phosphate was added to 1,000 g of the polyisocyanate p-2 obtained in Example 2, and the mixture was stirred at 50 ° C. for 1 hour in a nitrogen atmosphere to obtain a polyisocyanate composition P-6. The resulting polyisocyanate composition P-6 had a viscosity of 380 mPa.s. S (25 ° C.), NCO content 23.1% by mass, number average molecular weight 540, HDI monomer mass concentration 0.22%, and content of triethyl phosphate was 90 ppm. In addition, molecular weight stability after storage and yellowing during high temperature baking were evaluated. The obtained results are shown in Table 1.

(Example 7)
25 mg of triphenyl phosphate was added to 1,000 g of the polyisocyanate p-2 obtained in Example 2, and the mixture was stirred at 50 ° C. for 1 hour in a nitrogen atmosphere to obtain a polyisocyanate composition P-7. The resulting polyisocyanate composition P-7 had a viscosity of 380 mPa.s. S (25 degreeC), NCO content rate 23.2 mass%, number average molecular weight 540, content of triphenyl phosphate was 25 ppm. In addition, molecular weight stability after storage and yellowing during high temperature baking were evaluated. The obtained results are shown in Table 1.

(Example 8)
A four-necked flask equipped with a stirrer, thermometer, reflux condenser, nitrogen blowing tube, and dropping funnel was placed in a nitrogen atmosphere, charged with 6,000 g of HDI and 7.0 g of isobutanol, and the reactor temperature was 80 with stirring. The temperature was maintained at 2 ° C. for 2 hours. Thereafter, 5.0 g of a solution obtained by diluting the isocyanuration catalyst trimethyl-2-methyl-2-hydroxyethylammonium hydroxide with isobutanol to 5% by mass is added to conduct an isocyanuration reaction, and the NCO content of the reaction solution is When it reached 44.6% by mass, phosphoric acid was added to stop the reaction. The uretdione dimer concentration increased by this reaction was 1% by mass or less.

  The reaction solution was further maintained at 140 ° C. for 1 hour. This heating produced uretdione group-containing polyisocyanate. Using a thin film evaporator, purified twice under the conditions of 160 ° C. and 0.2 Torr, non-volatile content 99.5% by mass, viscosity 480 mPa · s (25 ° C.), NCO content 23.2% by mass, HDI monomer concentration 0.10% by mass of polyisocyanate p-3 was obtained. The molar ratio of uretdione group / isocyanurate group was 0.07.

  50 mg of triethyl phosphate was added to 1,000 g of the obtained polyisocyanate p-3, and the mixture was stirred at 50 ° C. for 1 hour in a nitrogen atmosphere to obtain a polyisocyanate composition P-8. The resulting polyisocyanate composition P-8 has a viscosity of 480 mPa.s. S (25 degreeC), NCO content rate 23.2 mass%, number average molecular weight 580, content of triethyl phosphate was 50 ppm. In addition, molecular weight stability after storage and yellowing during high temperature baking were evaluated. The obtained results are shown in Table 1.

Example 9
A four-necked flask equipped with a stirrer, thermometer, reflux condenser, nitrogen blowing tube, and dropping funnel was placed in a nitrogen atmosphere, and 6,000 g of HDI, 7.0 g of isobutanol and 6.0 g of triethyl phosphate were charged and stirred. The lower reactor internal temperature was maintained at 80 ° C. for 2 hours. Thereafter, 5.0 g of a solution obtained by diluting the isocyanuration catalyst trimethyl-2-methyl-2-hydroxyethylammonium hydroxide with isobutanol to 5% by mass is added to conduct an isocyanuration reaction, and the NCO content of the reaction solution is When it reached 44.6% by mass, phosphoric acid was added to stop the reaction. The uretdione dimer concentration increased by this reaction was 1% by mass or less.

  The reaction solution was further maintained at 160 ° C. for 1 hour. This heating produced uretdione group-containing polyisocyanate. Using a thin film evaporator, it was purified twice at 160 ° C. and 0.2 Torr, non-volatile content 99.5% by mass, viscosity 390 mPa · s (25 ° C.), NCO content 23.2% by mass, number average molecular weight A polyisocyanate composition P-9 having 530, an HDI monomer concentration of 0.12% by mass and a triethyl phosphate content of 12 ppm was obtained. The molar ratio of uretdione group / isocyanurate group was 0.32. The results are shown in Table 2.

(Comparative Example 1)
The polyisocyanate p-2 obtained in Example 2 was used as it was to obtain a polyisocyanate composition C-1. The content of the phosphate triester compound was not detected. (Lower detection limit 0.05 ppm) Further, the molecular weight stability after storage and the yellowing at the time of high temperature baking were evaluated. The obtained results are shown in Table 2.

(Comparative Example 2)
150 mg of triethyl phosphate was added to 1,000 g of the polyisocyanate p-2 obtained in Example 2, and the mixture was stirred at 50 ° C. for 1 hour in a nitrogen atmosphere to obtain a polyisocyanate composition C-2. The resulting polyisocyanate composition C-2 has a viscosity of 380 mPa.s. S (25 degreeC), NCO content rate 23.1 mass%, number average molecular weight 540, content of triethyl phosphate was 150 ppm. In addition, molecular weight stability after storage and yellowing during high temperature baking were evaluated. The obtained results are shown in Table 2.

(Comparative Example 3)
15 mg of dibutyl phosphate was added to 1,000 g of the polyisocyanate p-2 obtained in Example 2, and the mixture was stirred at 50 ° C. for 1 hour in a nitrogen atmosphere to obtain a polyisocyanate composition C-3. The resulting polyisocyanate composition C-3 had a viscosity of 390 mPa.s. S (25 ° C.), NCO content 23.2% by mass, number average molecular weight 540, and phosphate triester compound were not detected. (Lower detection limit 0.05 ppm) Further, the molecular weight stability after storage and the yellowing at the time of high temperature baking were evaluated. The obtained results are shown in Table 2.

(Comparative Example 4)
To 1,000 g of the polyisocyanate p-2 obtained in Example 2, 25 mg of polyphosphoric acid (manufactured by Kishida Chemical Co., Ltd.) was added, and the mixture was stirred at 50 ° C. for 1 hour in a nitrogen atmosphere to obtain a polyisocyanate composition C-4. Got. The resulting polyisocyanate composition C-4 had a viscosity of 410 mPa.s. S (25 ° C.), an NCO content of 23.1% by mass, a number average molecular weight of 540, and a phosphate triester compound were not detected. (Lower detection limit 0.05 ppm) Further, the molecular weight stability after storage and the yellowing at the time of high temperature baking were evaluated. The obtained results are shown in Table 2.

(Comparative Example 5)
20 mg of tributyl phosphite was added to 1,000 g of the polyisocyanate p-2 obtained in Example 2, and the mixture was stirred at 50 ° C. for 1 hour in a nitrogen atmosphere to obtain a polyisocyanate composition C-5. The resulting polyisocyanate composition C-5 has a viscosity of 400 mPa.s. S (25 ° C.), NCO content 23.2% by mass, number average molecular weight 540, and phosphate triester compound were not detected. (Lower detection limit 0.05 ppm) Further, the molecular weight stability after storage and the yellowing at the time of high temperature baking were evaluated. The obtained results are shown in Table 2.

  From the above, it was confirmed that the polyisocyanate composition of each Example had a small change in molecular weight after storage and small yellowing during baking.

  The coating composition using the polyisocyanate composition of the present invention as a curing agent can be used as a coating such as roll coating, curtain flow coating, spray coating, bell coating, and electrostatic coating. Furthermore, it can be used as a primer or top intermediate coating material for metals such as steel plates and surface-treated steel plates, and materials such as plastics, wood, films, and inorganic materials. Furthermore, it is also useful as a paint for imparting heat resistance, cosmetic properties (surface smoothness, sharpness), etc. to pre-coated metal including rust-proof steel plates, automobile coating, and the like. Furthermore, it is also useful as a urethane raw material for adhesives, pressure-sensitive adhesives, elastomers, foams, surface treatment agents and the like. Further, when used as a curing agent for water-based paints, it is possible to reduce the VOC component, so that it can be used in a wide range of fields as a raw material for water-based plastic paints and water-based automobile paints.

Claims (3)

A polyisocyanate obtained from an aliphatic diisocyanate unit containing 1,6-diisocyanatohexane and having an isocyanurate group and a uretdione group;
0.1 to 100 ppm by mass of a phosphoric acid triester compound represented by the following formula (I):
Containing a polyisocyanate composition.

(In formula, R < ₁ >, R < ₂ >, R < ₃ > may be the same or different, and represents a linear, branched or cyclic C1-C20 alkyl group or an aryl group.) A polyisocyanate composition according to claim 1;
An acrylic polyol having a hydroxyl value of 10 to 200 mgKOH / g and / or a polyester polyol having a hydroxyl value of 10 to 200 mgKOH / g;
A coating composition comprising:   A coating film obtained by curing the coating composition according to claim 2.