JP2017114959A - Block polyisocyanate composition, curable composition and article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a block polyisocyanate composition high in compatibility with an active hydrogen compound as a main agent and having low temperature curability.SOLUTION: There is provided a block polyisocyanate composition obtained from polyisocyanate obtained from one or more kind of diisocyanate selected from a group consisting of aliphatic diisocyanate and alicyclic diisocyanate, polyalkylene oxide having a specific structure and a block agent having one or more active hydrogen in a molecule, wherein concentration of trimer of which all isocyanates is blocked by the block agent is 25 mass% to 50 mass% and concentration of dimer of which all isocyanate groups is blocked by the block agent is 1.0 mass% to 20 mass% based on total amount of the block polyisocyanate composition.SELECTED DRAWING: None

Description

  The present invention relates to block polyisocyanate compositions, curable compositions, and articles.

  A polyurethane-based coating composition using a polyisocyanate composed of an aliphatic diisocyanate or an alicyclic diisocyanate as a curing agent is excellent in terms of chemical resistance, flexibility, weather resistance, and the like. Examples of the polyurethane coating composition include a room temperature curable two-pack type or a thermosetting one-pack type paint composition, depending on use conditions. In the one-pack type coating composition, a blocked polyisocyanate in which the isocyanate group of the polyisocyanate is protected by a thermally dissociable blocking agent is used. Even if it mixes with active hydrogen compounds, such as a polyol and polyamine which are main ingredients, block polyisocyanate does not react at normal temperature. By heating the mixture of the block polyisocyanate and the active hydrogen compound, the thermally dissociable blocking agent is dissociated to regenerate the isocyanate group, and the reaction between the block polyisocyanate and the active hydrogen compound proceeds. For this reason, it becomes possible to store in the state which mixed the main ingredient and the hardening | curing agent (block polyisocyanate) previously.

  For example, in Patent Document 1, a polyisocyanate in which a low molecular glycol having a side chain is one of the constituent units is used, and a blocked polyisocyanate blocked with a pyrazole-based compound can be baked at a low temperature. It is disclosed that it has excellent storage stability and a good coating film appearance. Patent Document 2 discloses a block polyisocyanate having an allophanate group, soluble in a low polarity solvent, and having low temperature curability.

JP 2000-178505 A JP 2011-208028 A

  A polyurethane-based coating composition using a blocked polyisocyanate as described in Patent Document 1 is used with a solvent added in order to ensure workability. However, in recent years, in order to reduce the burden on the global environment, it has been studied to reduce the amount of the solvent in the polyurethane-based coating composition. When reducing the amount of solvent, it is required that the compatibility between the block polyisocyanate and the active hydrogen compound as the main component is high.

  Block polyisocyanates are often inferior in compatibility with active hydrogen compounds compared to polyisocyanates. The block polyisocyanate described in any of Patent Documents 1 and 2 lacks compatibility with the active hydrogen compound, and further improvement is desired.

  Therefore, an object of the present invention is to provide a block polyisocyanate composition having high compatibility with an active hydrogen compound as a main agent and low temperature curability.

  As a result of intensive studies in order to solve the above-described problems of the prior art, the present inventors have obtained a specific polyisocyanate, a polyalkylene oxide, and a blocking agent, and the specific trimer and dimer concentrations are predetermined. The block polyisocyanate composition in the range has been found to have high compatibility with the active hydrogen compound as the main component and low temperature curability, and has led to the present invention.

（式（１）中、Ｒ₁は、炭素数３〜１０の炭化水素基を示し、Ｒ₂は、炭素数１〜１０の炭化水素基を示す。）
［２］
前記ポリアルキレンオキサイドの数平均分子量が、３００以上２０００以下である、［１］に記載のブロックポリイソシアネート組成物。
［３］
式（１）中のＲ₁は、プロピレン基を示す、［１］又は［２］に記載のブロックポリイソシアネート組成物。
［４］
前記ジイソシアネートは、少なくともヘキサメチレンジイソシアネートを含む、［１］〜［３］のいずれかに記載のブロックポリイソシアネート組成物。
［５］
前記ブロック剤は、少なくとも３，５−ジメチルピラゾールを含む、［１］〜［４］のいずれかに記載のブロックポリイソシアネート組成物。
［６］
少なくとも［１］〜［５］のいずれかに記載のブロックポリイソシアネート組成物を含む、硬化性組成物。
［７］
被着体と、該被着体を被覆する［６］に記載の硬化性組成物を硬化させた硬化物と、を備える、物品。 That is, the present invention has the following configuration.
[1]
A polyisocyanate obtained from one or two or more diisocyanates selected from the group consisting of aliphatic diisocyanates and alicyclic diisocyanates, a polyalkylene oxide represented by the following formula (1), and active hydrogen in the molecule A block polyisocyanate composition obtained from the block agent having one or more,
The concentration of the trimer in which all isocyanate groups are blocked with the blocking agent is 25% by mass or more and 50% by mass or less with respect to the total amount of the block polyisocyanate composition, and all the isocyanate groups are The block polyisocyanate composition whose density | concentration of the dimer blocked with the blocking agent is 1.0 mass% or more and 20 mass% or less.

(In formula (1), R ₁ represents a hydrocarbon group having 3 to 10 carbon atoms, and R ₂ represents a hydrocarbon group having 1 to 10 carbon atoms.)
[2]
The block polyisocyanate composition according to [1], wherein the polyalkylene oxide has a number average molecular weight of 300 or more and 2000 or less.
[3]
R ₁ in the formula (1) shows a propylene group, [1] or a blocked polyisocyanate composition according to [2].
[4]
The block polyisocyanate composition according to any one of [1] to [3], wherein the diisocyanate includes at least hexamethylene diisocyanate.
[5]
The blocked polyisocyanate composition according to any one of [1] to [4], wherein the blocking agent contains at least 3,5-dimethylpyrazole.
[6]
A curable composition containing the block polyisocyanate composition according to any one of [1] to [5].
[7]
An article comprising an adherend and a cured product obtained by curing the curable composition according to [6] that covers the adherend.

  The block polyisocyanate composition according to the present invention simultaneously achieves high compatibility with the active hydrogen compound as the main agent and low temperature curability.

  DESCRIPTION OF EMBODIMENTS Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail. However, the present invention is not limited to this, and various modifications can be made without departing from the gist thereof. Is possible.

式（１）中、Ｒ₁は、炭素数３〜１０の炭化水素基を示し、Ｒ₂は、炭素数１〜１０の炭化水素基を示す。 [Block polyisocyanate composition]
The block polyisocyanate composition of the present embodiment is represented by the following formula (1): a polyisocyanate obtained from one or more diisocyanates selected from the group consisting of aliphatic diisocyanates and alicyclic diisocyanates. It is obtained from a polyalkylene oxide and a blocking agent having at least one active hydrogen in the molecule.

In formula (1), R ₁ represents a hydrocarbon group having 3 to 10 carbon atoms, and R ₂ represents a hydrocarbon group having 1 to 10 carbon atoms.

  The block polyisocyanate composition is a trimer in which all isocyanate groups are blocked with a blocking agent with respect to the total amount (100% by mass) of the block polyisocyanate composition (hereinafter referred to as “total block trimer”). Of the dimer (hereinafter also referred to as “all block dimer”) in which all isocyanate groups are blocked with a blocking agent. The concentration is 1.0 mass% or more and 20 mass% or less.

  Examples of the total block trimer include those in which all (three) isocyanate groups of a trimer containing an isocyanurate group and an iminooxadiazinedione group are blocked with a blocking agent. Or 2 or more types may be contained, but it is preferable that an isocyanurate group is included from the viewpoint of the weather resistance and curability of the coating film obtained from the block polyisocyanate composition. The density | concentration of all the block trimers is 25 to 50 mass% with respect to the total amount (100 mass%) of a block polyisocyanate composition, and it is preferable that it is 28 to 45 mass%. When the concentration is in the range of 25% by mass or more and 50% by mass or less, good curability can be obtained. The concentration can be determined by the method described in the examples. The concentration can be adjusted by adjusting the mass concentration of the polyisocyanate trimer to be used, the addition amount of the polyalkylene oxide, and the addition amount of the blocking agent.

  Examples of the total block dimer include those in which all (two) isocyanate groups of a dimer containing a uretdione group are blocked with a blocking agent, and one or two or more types are included. However, from the viewpoint of leveling properties of the paint obtained from the block polyisocyanate composition, it is preferable to contain a uretdione group. The density | concentration of all the block dimers is 1.0 mass% or more and 20 mass% or less with respect to the total amount (100 mass%) of a block polyisocyanate composition, and 2.0 mass from a viewpoint of the leveling property of a coating material. % To 15% by mass, more preferably 5.0% to 15% by mass. When the concentration is in the range of 1.0% by mass or more and 20% by mass or less, good compatibility can be obtained. The concentration can be determined by the method described in the examples. The concentration can be adjusted by adjusting the mass concentration of the polyisocyanate dimer used, the addition amount of the polyalkylene oxide, and the addition amount of the blocking agent.

  The block polyisocyanate composition preferably further has an allophanate group. The allophanate group is a chemical bond formed from two isocyanate groups and one hydroxyl group, and is formed, for example, by a reaction between a compound having a hydroxyl group and diisocyanate. Examples of the compound having a hydroxyl group include a monoalcohol having one hydroxyl group and a diol having two hydroxyl groups, and a monoalcohol is preferable. The lower limit of the carbon number of the monoalcohol is preferably 2, more preferably 3, still more preferably 4, and still more preferably 6 from the viewpoint of the weather resistance of the coating film. The upper limit of the carbon number is preferably 16, more preferably 12, and still more preferably 9 from the viewpoint of coating film hardness. Monoalcohol may be used individually by 1 type and may use 2 or more types together.

  The alcohol may contain an ether group, an ester group, or a carbonyl group in the molecule, but a monoalcohol consisting only of a saturated hydrocarbon group is more preferable. Moreover, the monoalcohol which has a branch is more preferable from a viewpoint of viscosity reduction and compatibility with an active hydrogen compound.

  These specific monoalcohols are not particularly limited. For example, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutanol, 1-pentanol, 2-pentanol, Isoamyl alcohol, 1-hexanol, 2-hexanol, 1-heptanol, 1-octanol, 2-ethyl-1-hexanol, 3,5,5-trimethyl-1-hexanol, tridecanol, pentadecanol, palmityl alcohol, stearyl Examples include alcohol, cyclopentanol, cyclohexanol, methylcyclohexanol, and trimethylcyclohexanol. Among these, isobutanol, 1-butanol, isoamyl alcohol, 1-hexanol, 1-heptanol, 1-octanol, 2-ethyl-1-hexanol, tridecanol, pentadecanol, palmityl alcohol, stearyl alcohol, and 3 , 5,5-trimethyl-1-cyclohexanol, more preferably isobutanol, isoamyl alcohol, and 2-ethyl-1-hexanol.

  Moreover, you may use diol together as needed. Specific examples of the diol are not particularly limited. For example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,2-propanediol, 1,3-propanediol, 1, 2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 2-methyl-1,2-propanediol, 1,5-pentanediol, 2-methyl-2, 3-butanediol, 1,6-hexanediol, 1,2-hexanediol, 2,5-hexanediol, 2-methyl-2,4-pentanediol, 2,3-dimethyl-2,3-butanediol, 2-ethyl-hexanediol, 1,2-octanediol, 1,2-deca Diol, 2,2,4-trimethylpentane diol, 2-butyl-2-ethyl-1,3-propanediol, and 2,2-diethyl-1,3-propanediol and the like.

  In the block polyisocyanate composition, the allophanate group concentration is preferably 0.5 mol% or more and 10 mol% or less, and 1.0 mol% with respect to all isocyanurate groups contained in the block polyisocyanate composition. More preferably, it is 10 mol% or less, and further preferably 1.0 mol% or more and 5.0 mol% or less. Within this range, the compatibility with the polyol tends to be further improved while maintaining curability. In order to obtain a blocked polyisocyanate composition in such a range, it is preferable to urethanate the alcohol and the diisocyanate, and thereafter or simultaneously perform an allophanatization reaction. The reaction temperature of this urethanization reaction is preferably 20 to 200 ° C., more preferably 40 to 150 ° C., and still more preferably 60 to 120 ° C. in terms of production efficiency and suppression of coloring. The reaction time is preferably 10 minutes to 24 hours, more preferably 15 minutes to 15 hours, and even more preferably 20 minutes to 10 hours in terms of production efficiency and side reaction suppression.

  The allophanatization reaction is preferably performed at a temperature of 20 to 200 ° C. in terms of production efficiency and coloring suppression. More preferably, it is 60-160 degreeC. More preferably, it is 90-150 degreeC, More preferably, it is 110-150 degreeC. The reaction time of the allophanatization reaction is preferably 10 minutes to 24 hours, more preferably 15 minutes to 12 hours, further preferably 20 minutes to 8 hours, and even more preferably 20 in terms of production efficiency and side reaction suppression. Min to 6 hours. The allophanate group concentration is measured by the method described in Examples described later.

  The effective isocyanate group content (%) in the block polyisocyanate composition is preferably 8.0% or more and 12% or less.

  A block polyisocyanate composition can be diluted with a solvent as needed and coated without mixing a component that reacts with a blocked isocyanate group. The applied block polyisocyanate composition can be imparted with characteristics by the reaction with functional groups such as hydroxyl groups of the base material or reaction between isocyanate groups by dissociation of the thermally dissociable blocking agent bonded to the heated isocyanate groups.

  The block polyisocyanate can also be dispersed in water using an emulsifier. Examples of the emulsifier include anionic compounds having a carboxyl group and the like; cationic systems having an amino group and the like; and nonionic compounds having an ether group and the like.

<Polyisocyanate>
The polyisocyanate of this embodiment is a polyisocyanate multimer (formed from two or more diisocyanate molecules) obtained from one or more diisocyanates selected from the group consisting of aliphatic diisocyanates and alicyclic diisocyanates. Multimers).

  The polyisocyanate is not particularly limited, but is selected from the group consisting of, for example, isocyanurate groups, iminooxadiazinedione groups, uretdione groups, allophanate groups, biuret groups, oxadiazinetrione groups, urea groups, and urethane groups. And polyisocyanates having one or more bonds.

  The number average molecular weight in the polyisocyanate is preferably 100 or more and 5000 or less.

  The viscosity of the polyisocyanate is preferably 300 mPas / 25 ° C. or higher and 1000 mPas / 25 ° C. or lower.

  The isocyanate group concentration (%) in the polyisocyanate is preferably 15% or more and 30% or less.

  In the present embodiment, the “aliphatic diisocyanate” refers to a compound having a chain aliphatic hydrocarbon and no aromatic hydrocarbon when an isocyanate group is excluded from the molecule. The aliphatic diisocyanate is not particularly limited, and examples thereof include butane diisocyanate, pentane diisocyanate, hexamethylene diisocyanate (hereinafter also referred to as “HDI”), trimethylhexamethylene diisocyanate, and lysine diisocyanate. It is more preferable to use a polyisocyanate derived from such an aliphatic diisocyanate because the resulting polyisocyanate tends to have a low viscosity.

  In the present embodiment, “alicyclic diisocyanate” refers to a compound having a cyclic aliphatic hydrocarbon having no aromaticity in the molecule. Although it does not specifically limit as alicyclic diisocyanate, For example, isophorone diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated diphenylmethane diisocyanate, and 1, 4- cyclohexane diisocyanate are mentioned.

  Among the aliphatic diisocyanates and alicyclic diisocyanates, HDI, isophorone diisocyanate, hydrogenated xylylene diisocyanate, and hydrogenated diphenylmethane diisocyanate are preferable because they are easily available industrially, and HDI is more preferable. Therefore, it is more preferable that the diisocyanate of this embodiment contains HDI. By using HDI, the weather resistance of the coating film obtained from the block polyisocyanate composition tends to be more excellent.

  The mass concentration of the aliphatic diisocyanate monomer unit constituting the block polyisocyanate composition is preferably 30% by mass to 60% by mass, and more preferably 40% by mass to 60% by mass.

<Method for producing polyisocyanate>
The polyisocyanate production method includes a method of producing a trimer and a dimer simultaneously or separately, and includes a step of producing a trimer having an isocyanurate group and a dimer having a uretdione group. It is preferable.

  The polyisocyanate having an isocyanurate group can be obtained, for example, by carrying out an isocyanuration reaction with a catalyst or the like. The isocyanuration reaction is stopped when the predetermined conversion rate (mass ratio of raw materials for constituting the polyisocyanate in the reaction liquid of the polyisocyanate produced by the isocyanuration reaction) is reached, and the diisocyanate monomer is removed. It is done.

  As the isocyanuration reaction catalyst used in this case, for example, a catalyst having basicity is generally preferred. (A) Tetraalkylammonium hydroxide such as tetramethylammonium and tetraethylammonium, for example, acetic acid, capric acid and the like Weak organic acid salt, (b) hydroxyalkylammonium hydroxide such as trimethylhydroxypropylammonium, trimethylhydroxyethylammonium, triethylhydroxypropylammonium and triethylhydroxyethylammonium, and weak organic acid salt such as acetic acid and capric acid, (c) Alkali metal salts of alkyl carboxylic acids such as acetic acid, caproic acid, octylic acid and myristic acid, such as tin, zinc and lead; (d) metals such as sodium and potassium (E) aminosilyl group-containing compounds such as hexamethyldisilazane, (f) Mannich bases, (g) combined use of tertiary amines and epoxy compounds, (h) phosphorus compounds such as tributylphosphine Is mentioned. The amount of these catalysts used is selected from the range of 10 ppm by mass or more and 1.0% by mass with respect to the total mass of the diisocyanate and alcohol as raw materials. In order to terminate the reaction, these are inactivated by, for example, addition of an acidic substance such as phosphoric acid or acidic phosphoric acid ester that neutralizes the catalyst, thermal decomposition, or chemical decomposition.

  The polyisocyanate having an iminooxadiazinedione group is not particularly limited. For example, a catalyst or the like can be used. As this method, for example, a method described in JP-A-2004-534870 can be used.

  The polyisocyanate component having a biuret group can be prepared by reacting one or more diisocyanates selected from the group consisting of aliphatic diisocyanates and alicyclic diisocyanates with a biuret agent. Although it does not specifically limit as a biuret agent, For example, water, monohydric tertiary alcohol, formic acid, hydrogen sulfide, organic primary monoamine, and organic primary diamine are mentioned, Preferably it is water.

  The biuretization reaction temperature is preferably 70 ° C. or higher and 200 ° C. or lower, and more preferably 90 ° C. or higher and 180 ° C. or lower.

  The uretdione formation reaction which produces | generates a uretdione dimer can be performed by the method of using a catalyst, and / or the method by a heating. The method using a catalyst includes a method using an isocyanuration reaction catalyst and a method using a uretdione reaction catalyst.

  Specific examples of the uretdione reaction catalyst include, for example, tertiary phosphine, trialkylphosphine such as tri-n-butylphosphine and tri-n-octylphosphine; trisphosphine such as tris- (dimethylamino) phosphine. (Dialkylamino) phosphine; cycloalkylphosphine such as cyclohexyl-di-n-hexylphosphine. 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 reached, a quencher for the uretdione reaction catalyst such as phosphoric acid or methyl paratoluenesulfonate is added to stop the uretdione reaction.

  When a uretdione group is formed by heat without using a catalyst, the heating temperature is 120 ° C. or higher, preferably 150 ° C. to 170 ° C., and the heating time is preferably 1.0 to 4.0 hours.

  The uretdione reaction can be carried out after or before the end of the isocyanuration reaction.

  The allophanatization reaction for generating an allophanate group can be carried out by a catalyst and heat. However, when using a catalyst, the allophanate reaction can be carried out more efficiently than by heat.

  The specific allophanatization catalyst is not particularly limited, and examples thereof include alkyl carboxylates such as tin, lead, zinc, bismuth, zirconium and zirconyl, and organic compounds such as tin 2-ethylhexanoate and dibutyltin dilaurate. Tin compounds; organic lead compounds such as lead 2-ethylhexanoate; organic zinc compounds such as zinc 2-ethylhexanoate, bismuth 2-ethylhexanoate, zirconium 2-ethylhexanoate, and zirconyl 2-ethylhexanoate It is done. Two or more of these may be used in combination.

  An isocyanurate-forming catalyst can also be an allophanatization catalyst. When an allophanate reaction is carried out using an isocyanurate-forming catalyst, an isocyanurate group-containing polyisocyanate can also be produced simultaneously.

  Since the polyisocyanate preferably contains both an isocyanurate group and an allophanate group, it is preferable for economical production to perform an allophanate reaction and an isocyanurate reaction using an isocyanurate reaction catalyst.

  The allophanate group concentration in the polyisocyanate is preferably 0.5 mol% or more and 10 mol% or less, and 1.0 mol% or more and 10 mol% or less with respect to all isocyanurate groups contained in the polyisocyanate. More preferably, it is 1.0 mol% or more and 5.0 mol% or less. Within this range, the compatibility with the polyol tends to be further improved while maintaining curability. The lophanate group concentration is measured by the method described in Examples described later.

  The concentration of the diisocyanate monomer trimer in the polyisocyanate is preferably 40% by mass or more and 99% by mass or less, and can be controlled by setting the conversion rate. Within this range, the curability tends to be good. The mass concentration of the trimer is measured by the method described in Examples described later.

  From the above viewpoint, the conversion rate of the polyisocyanate is preferably 10% by mass or more and 50% by mass or less, and more preferably 15% by mass or more and 45% by mass or less.

The “yield” is the same value as the conversion rate. This is because all converted components become polyisocyanates.

  The concentration of the diisocyanate monomer dimer in the polyisocyanate is preferably 1.0% by mass or more and 20% by mass or less. If it is within this range, the viscosity of the paint tends to decrease and the leveling property tends to be good. The monomer concentration is measured by the method described in Examples described later.

式（１）中、Ｒ₁は、炭素数３〜１０の炭化水素基を示し、Ｒ₂は、炭素数１〜１０の炭化水素基を示す。 <Polyalkylene oxide>
The polyalkylene oxide of this embodiment is represented by the following formula (1). This is, for example, a polymer having one hydroxyl group by addition polymerization of a C 3-10 alkylene oxide to a hydroxyl group of a monoalcohol.

In formula (1), R ₁ represents a hydrocarbon group having 3 to 10 carbon atoms, and R ₂ represents a hydrocarbon group having 1 to 10 carbon atoms.

  The monoalcohol has 1 to 10 carbon atoms, preferably 2 to 8 carbon atoms, and more preferably 4 to 8 carbon atoms. Specific examples of these monoalcohols include methanol, ethanol, 2-propanol, n-butanol, sec-butanol, and 2-ethyl-1-hexanol.

Examples of the alkylene oxide having 3 to 10 carbon atoms include propylene oxide, butylene oxide, cyclohexene oxide, and styrene oxide, and propylene oxide is preferable. That is, it is preferable that R ₁ in the above formula (1) is a polyalkylene oxide showing a propylene group. These alkylene oxides may be linear or branched.

  The catalyst for adding these polyalkylene oxides alone or in a mixture to the above monoalcohol is not particularly limited. For example, hydroxides such as lithium, sodium and potassium; strong basic catalysts such as alcoholates and alkylamines. A complex metal cyanide complex such as metal porphyrin and zinc hexacyanocobaltate complex;

  The number average molecular weight of the polyalkylene oxide is preferably 300 or more and 2000 or less, more preferably 300 or more and 1500 or less, and further preferably 300 or more and 1000 or less. Alkylene oxides in this range are preferred because they tend to be compatible with the polyol and to the hardness of the coating film obtained from the paint containing the block polyisocyanate using the polyol.

  The concentration of the polyalkylene oxide unit in the block polyisocyanate composition is preferably 10% by mass or more and 50% by mass or less. When the concentration is 10% by mass or more, the compatibility with the main agent is improved, and when the concentration is 50% by mass or less, the curability and the strength of the coating film tend to be good. The concentration is more preferably 12% by mass or more and 50% by mass or less, further preferably 14% by mass or more and 45% by mass or less, and further preferably 16% by mass or more and 40% by mass or less. The alkylene oxide unit concentration may be calculated from the charging ratio.

[Block agent]
The blocking agent of this embodiment is a compound having at least one active hydrogen in the molecule. Although it does not specifically limit as a blocking agent, For example, alkylphenol type, phenol type, active methylene type, mercaptan type, acid amide type, acid imide type, imidazole type, urea type, oxime type, amine type, imide type, and pyrazole Compounds of the system. Examples of more specific blocking agents are shown below.
(1) Alkylphenol-based mono- and dialkylphenols having an alkyl group having 4 or more carbon atoms as a substituent, such as n-propylphenol, i-propylphenol, n-butylphenol, sec-butylphenol, t-butylphenol , N-hexylphenol, 2-ethylhexylphenol, n-octylphenol, n-nonylphenol and other monoalkylphenols, di-n-propylphenol, diisopropylphenol, isopropylcresol, di-n-butylphenol, di-t-butylphenol, di- Dialkylphenols such as -sec-butylphenol, di-n-octylphenol, di-2-ethylhexylphenol, di-n-nonylphenol,
(2) phenolic; phenol, cresol, ethylphenol, styrenated phenol, hydroxybenzoic acid ester,
(3) Active methylene type: dimethyl malonate, diethyl malonate, methyl acetoacetate, ethyl acetoacetate, acetylacetone,
(4) Mercaptan series; butyl mercaptan, dodecyl mercaptan,
(5) Acid amide system: acetanilide, acetic acid amide, ε-caprolactam, δ-valerolactam, γ-butyrolactam,
(6) Acid imide type; succinimide, maleic imide,
(7) Imidazole series; imidazole, 2-methylimidazole,
(8) Urea system; urea, thiourea, ethylene urea,
(9) Oxime series: formaldoxime, acetaldoxime, acetoxime,
Methyl ethyl ketoxime, cyclohexanone oxime,
(10) Amine system; diphenylamine, aniline, carbazole, di-n-propylamine, diisopropylamine, isopropylethylamine,
(11) Imine type; ethyleneimine, polyethyleneimine,
(12) pyrazole series; pyrazole, 3-methylpyrazole, 3,5-dimethylpyrazole,
Is mentioned. Two or more of these may be used in combination.

  Among the above, the blocking agent is preferably amines, pyrazoles, imidazoles, triazoles, imines, and acid amides, more preferably amines and pyrazoles, and further preferably pyrazoles. And more preferably 3,5-dimethylpyrazole is contained. By including a blocked isocyanate group in which an isocyanate group is blocked with such a blocking agent, the low temperature curability tends to be superior.

  The block polyisocyanate has a highly polar group obtained by reacting a blocking agent with an isocyanate group. On the other hand, the bond formed by the amino group and the isocyanate group of the pyrazole compound tends to form a hydrogen bond, and the compatibility tends not to be high.

  Under such circumstances, the compatibility is remarkably improved by specifying the constituent components and the concentration of the block polyisocyanate composition. Furthermore, it leads to having good curability.

  In the block polyisocyanate composition, the concentration of the blocking agent that reacts with the isocyanate group is preferably 15% by mass or more and 30% by mass or less. Within this range, the low-temperature curability and compatibility tend to be better.

  Although the manufacturing method of the block polyisocyanate composition of this embodiment is not specifically limited, For example, polyisocyanate is manufactured first, The polyalkylene oxide of this embodiment and the blocking agent of this embodiment are added to the isocyanate group of the polyisocyanate. Examples of the method include addition reaction. The addition reaction of the polyalkylene oxide and the addition reaction of the blocking agent may be performed independently or simultaneously.

  In order to produce a block polyisocyanate composition, each step of production of polyisocyanate, addition reaction of polyalkylene oxide, and blocking agent is carried out by first producing polyisocyanate, adding polyalkylene oxide, and then blocking agent. Is preferably subjected to an addition reaction.

  The temperature of the addition reaction of the polyalkylene oxide in the addition reaction of the polyalkylene oxide and the blocking agent to the polyisocyanate produced by the production method described above is preferably 50 to 100 ° C, and 70 to 90 ° C. Is more preferable. The reaction time is preferably 1.0 hour to 5.0 hours, more preferably 2.0 to 4.0 hours.

  A solvent can be used in the production of polyisocyanate, polyalkylene oxide addition reaction, and blocking agent addition reaction.

  When using a solvent, it is preferable to use a solvent inert to the isocyanate group. Examples of the solvent include ketone solvents such as acetone and methyl ethyl ketone; and ester solvents such as ethyl acetate and butyl acetate. After all the isocyanate groups are blocked with a blocking agent, an alcohol solvent can be added for dilution. Examples of the alcohol solvent include 1-butanol, 2-propanol, dipropylene glycol monomethyl ether, and dipropylene glycol dimethyl ether.

(Curable composition)
The curable composition of this embodiment includes at least the block polyisocyanate composition of this embodiment. Moreover, the active hydrogen compound (polyvalent active hydrogen compound) which does not contain an organic solvent substantially can be included as a main ingredient. When this curable composition is heated, the thermally dissociable blocking agent bonded to the isocyanate group is dissociated, and the isocyanate group and the active hydrogen in the active hydrogen compound react to form a cured product. .

  The active hydrogen compound is a compound in which two or more active hydrogens are bonded in the molecule, and includes polyols, polyamines, polythiols, and the like, but many use polyols.

  Although it does not specifically limit as said polyol, For example, acrylic polyol, polyester polyol, polyether polyol, polyolefin polyol, fluorine polyol, polycarbonate polyol, and an epoxy resin are mentioned.

  An acrylic polyol is a polymerizable monomer having active hydrogen, and specific examples thereof include, but are not particularly limited to, for example, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate Acrylic acid monoester or methacrylic acid monoester of glycerol, acrylic acid monoester or methacrylic acid monoester of trimethylolpropane, methacrylic acid-2-hydroxyethyl, methacrylic acid-2-hydroxypropyl, methacrylic acid Methacrylic acid esters such as 2-hydroxybutyl, methacrylic acid-3-hydroxypropyl, methacrylic acid-4-hydroxybutyl, etc. are essential, and if necessary, methyl acrylate, ethyl acrylate, isopropyl acrylate, Acrylic esters such as -n-butyl crylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, -n-butyl methacrylate, isobutyl methacrylate, -n-hexyl methacrylate, methacryl Methacrylic acid esters such as lauryl acid, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid and itaconic acid, unsaturated amides such as acrylamide, N-methylolacrylamide and diacetoneacrylamide, and glycidyl methacrylate, styrene and vinyl Bis having hydrolyzable silyl groups such as toluene, vinyl acetate, acrylonitrile, dibutyl fumarate, vinyltrimethoxysilane, vinylmethyldimethoxysilane, and γ- (meth) acryloxypropyltrimethoxysilane. Examples include acrylic polyols obtained by polymerizing a single monomer or a mixture selected from nil monomers.

  The polyester polyol is not particularly limited. For example, a dibasic acid selected from the group consisting of carboxylic acids such as succinic acid, adipic acid, sebacic acid, dimer acid, maleic anhydride, phthalic anhydride, isophthalic acid, and terephthalic acid. A polyester polyol obtained by a condensation reaction of a single or a mixture of a polyhydric alcohol selected from the group consisting of ethylene glycol, propylene glycol, diethylene glycol, neopentyl glycol, trimethylolpropane, glycerin and the like, and ε -Polycaprolactones obtained by ring-opening polymerization of caprolactone to polyhydric alcohols. These polyester polyols can also be modified with aromatic diisocyanates, aliphatic and alicyclic diisocyanates and polyisocyanates obtained therefrom. In this case, aliphatic and alicyclic diisocyanates and polyisocyanates obtained therefrom are preferred from the weather resistance and yellowing resistance.

  The polyether polyols are not particularly limited, but for example, using a polybasic hydroxy compound alone or in a mixture, a hydroxide such as lithium, sodium or potassium, an alcoholate, or a strongly basic catalyst such as an alkylamine, Polyether polyols obtained by adding an alkylene oxide such as ethylene oxide, propylene oxide, butylene oxide, cyclohexene oxide, and styrene oxide alone or in a mixture, and further obtained by reacting an alkylene oxide with a polyfunctional compound such as ethylenediamine. Examples include ether polyols and so-called polymer polyols obtained by polymerizing acrylamide or the like using these polyethers as a medium.

As the polyvalent hydroxy compound,
(1) For example, diglycerin, ditrimethylolpropane, pentaerythritol, and dipentaerythritol,
(2) For example, sugar alcohol compounds such as erythritol, D-threitol, L-arabinitol, ribitol, xylitol, sorbitol, mannitol, galactitol, rhamnitol,
(3) For example, monosaccharides such as arabinose, ribose, xylose, glucose, mannose, galactose, fructose, sorbose, rhamnose, fucose, ribodesource,
(4) For example, disaccharides such as trehalose, sucrose, maltose, cellobiose, gentiobiose, lactose, melibiose,
(5) For example, trisaccharides such as raffinose, gentianose, and meletitose,
(6) For example, tetrasaccharides such as stachyose,
Is mentioned.

  Preferred polyols are acrylic polyols and polyester polyols, with acrylic polyols being more preferred.

  The hydroxyl group value of the polyol is preferably 30 mgKOH / g or more and 300 mgKOH / g or less, more preferably 30 mgKOH / g or more and 200 mgKOH / g or less, from the viewpoint of crosslink density and mechanical properties of the cured resin. If necessary, the acid value of the polyol may be in the range of 30 mgKOH / g to 50 mg / KOH. The glass transition point of the polyol is preferably -20 ° C or higher and 100 ° C or lower. In the case of acrylic polyol, the glass transition point can be calculated from the well-known Fox equation.

  In the curable composition, the equivalent ratio of the blocked isocyanate group of the blocked polyisocyanate to the hydroxyl group of the polyol is preferably from 1/5 to 5/1, more preferably from 3/5 to 5/3, and even more preferably 4 / 5 or more and 5/4 or less.

  In the curable composition, for example, a melamine curing agent and another curing agent of an epoxy curing agent may be used in combination. Although it does not specifically limit as a melamine type hardening | curing agent, For example, the fully alkyl etherified melamine resin, the methylol group type melamine resin, and the imino group type melamine resin which has an imino group in part are mentioned. When a melamine curing agent is used in combination, the addition of an acidic compound is effective. Specific examples of the acidic compound include carboxylic acid, sulfonic acid, acidic phosphate ester, and phosphite ester.

  Examples of the carboxylic acid include, but are not particularly limited to, for example, acetic acid, lactic acid, succinic acid, oxalic acid, maleic acid, and decanedicarboxylic acid, and the sulfonic acid is not particularly limited. Examples include sulfonic acid, dodecylbenzene sulfonic acid, and dinonylnaphthalenedisulfonic acid. The acidic phosphate ester is not particularly limited, and examples thereof include dimethyl phosphate, diethyl phosphate, dibutyl phosphate, dioctyl phosphate, dilauryl phosphate, monomethyl phosphate, monoethyl phosphate, monobutyl phosphate, and monooctyl phosphate. Phosphites include diethyl phosphite, dibutyl phosphite, dioctyl phosphite, dilauryl phosphite, monoethyl phosphite, monobutyl phosphite, monooctyl phosphite, and monolauryl phosphite.

  Various organic solvents and additives can be used for the curable composition depending on the application and purpose. The organic solvent is not particularly limited as long as the reaction with an isocyanate group does not proceed. For example, aliphatic hydrocarbon solvents such as hexane, heptane, and octane; alicyclic hydrocarbon solvents such as cyclohexane and methylcyclohexane ; Ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone; ester solvents such as methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, methyl lactate, ethyl lactate; toluene, xylene, diethylbenzene, mesitylene, anisole, benzyl Aromatic solvents such as alcohol, phenyl glycol, chlorobenzene; ethylene glycol monoethyl ether acetate, 3-methyl-3-methoxybutyl acetate, dipropylene glycol monomethyl ether, propylene glycol Glycol solvents such as monoethyl ether; ether solvents such as diethyl ether, tetrahydrofuran and dioxane; halogenated hydrocarbon solvents such as dichloromethane, 1,2-dichloroethane and chloroform; pyrrolidones such as N-methyl-2-pyrrolidone Amide solvents such as N, N-dimethylacetamide and N, N-dimethylformamide; sulfoxide solvents such as dimethyl sulfoxide; lactone solvents such as γ-butyrolactone; amine solvents such as morpholine; and mixtures thereof Is mentioned.

  In addition, a curing accelerating catalyst, an antioxidant, an ultraviolet absorber, a light stabilizer, a pigment, a leveling agent, a plasticizer, a surfactant, and various active agents are used for the curable composition depending on the purpose and application. be able to.

  Although it does not specifically limit as a hardening acceleration | stimulation catalyst, For example, tin-type compounds, such as dibutyltin dilaurate, dibutyltin diacetate, dioctyltin dilaurate, dimethyltin dineodecanoate, bis (2-ethylhexanoic acid) tin; 2-ethyl Zinc compounds such as zinc hexanoate and zinc naphthenate; titanium compounds such as titanium 2-ethylhexanoate and titanium diisopropoxybis (ethylacetonate); cobalt compounds such as cobalt 2-ethylhexanoate and cobalt naphthenate; 2 -Bismuth compounds such as bismuth ethylhexanoate and bismuth naphthenate; zirconium compounds such as zirconium tetraacetylacetonate, zirconyl 2-ethylhexanoate and zirconyl naphthenate; and amine compounds. Although it does not specifically limit as antioxidant, For example, a hindered phenol type, phosphorus type, and a sulfur type compound are mentioned. Although it does not specifically limit as a ultraviolet absorber, For example, a benzotriazole type, a triazine type | system | group, a benzophenone type compound is mentioned. The light stabilizer is not particularly limited, and examples thereof include hindered amines, benzotriazoles, triazines, benzophenones, and benzoates. Although it does not specifically limit as a pigment, For example, a titanium oxide, carbon black, indigo, pearl mica, and aluminum are mentioned. Although it does not specifically limit as a leveling agent, For example, a silicone oil is mentioned. Although it does not specifically limit as a plasticizer, For example, phthalic acid esters, phosphoric acid type, and polyester type are mentioned. Although it does not specifically limit as surfactant, For example, a well-known anionic surfactant, a cationic surfactant, and an amphoteric surfactant are mentioned.

  The curable composition of this embodiment is used for, for example, a coating composition, a pressure-sensitive adhesive composition, an adhesive composition, and a casting composition, and various surface treatment compositions such as a fiber treatment agent; Various elastomer compositions; cross-linking agents such as foam compositions; modifiers; can also be used as additives.

  The coating composition of the present embodiment is not particularly limited, but is suitably used as a primer, intermediate coating, or top coating on various materials by, for example, roll coating, curtain flow coating, spray coating, electrostatic coating, and bell coating. sell. In addition, this coating composition can be applied to, for example, pre-coated metal including an anticorrosive steel plate, automobiles, plastics, and electronic substrates, with cosmetic properties, weather resistance, acid resistance, rust resistance, chipping resistance, insulation, and adhesion. It is suitably used for imparting.

  Although the adhesive composition and adhesive composition of this embodiment are not specifically limited, For example, it can be used in the field | area of the laminated body for motor vehicles, building materials, household appliances, woodwork, and a solar cell. For example, home appliances such as a television, a personal computer, a digital camera, and a mobile phone need to be laminated with films and plates of various adherends in order to develop various functions in optical members for liquid crystal displays and the like. Therefore, since sufficient tackiness or adhesiveness is required between the film and the plate of various adherends, the home appliance including the optical member is the pressure-sensitive adhesive composition of the present embodiment and the adhesive composition. It is preferable as an example of use.

[Articles]
The article of the present embodiment includes an adherend and a cured product obtained by curing the curable composition of the present embodiment that covers the adherend. The adherend that can be an article coated with the cured product of the present embodiment is not particularly limited. For example, glass; various metals such as aluminum, iron, galvanized steel, copper, and stainless steel; wood, paper, mortar, Porous material such as stone; Fluorine coating, urethane coating, acrylic urethane coating, etc .; Silicone-based cured products, modified silicone-based cured products, urethane-based cured products, etc .; Vinyl chloride, natural rubber , Rubbers such as synthetic rubber; leathers such as natural leather and artificial leather; fibers such as plant fibers, animal fibers, carbon fibers and glass fibers; non-woven fabrics, polyesters, acrylics, polycarbonates, triacetyl celluloses, polyolefins, etc. Resin films and plates; UV-curable acrylic resin layers, printing inks, UV inks and other inks That.

  Hereinafter, the present embodiment will be described in more detail based on examples, but the present embodiment is not limited to the following examples. First, the physical properties and measurement methods for evaluation and evaluation criteria will be described below. In the following, “parts” and “%” indicating the amount or ratio of a product mean values based on mass unless otherwise specified.

(Physical property 1) Number average molecular weight Using the polyisocyanate obtained in each synthesis example as a sample, the number average molecular weight was measured as a number average molecular weight based on polystyrene by gel permeation chromatography using the following apparatus.
Equipment: Tosoh Corporation HLC-802A
Column: Tosoh Corporation G1000HXL x 1
G2000HXL 〃
G3000HXL 〃
Carrier: Tetrahydrofuran Detection method: Differential refractometer

(Physical Property 2) Viscosity Using the polyisocyanate obtained in each synthesis example as a sample, the viscosity was measured at 25 ° C. using an E-type viscometer manufactured by Toki Sangyo Co., Ltd. The measurement was made with an E-type viscometer (manufactured by Tokimec Co., Ltd.), and a standard rotor (1 ° 34 ′ × R24) was used as the rotor. The number of rotations was as follows.
100r. p. m. (If 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. (In the case of 640 mPa · s or more and less than 1,280 mPa · s)
5r. p. m. (In the case of 1,280 mPa · s or more and less than 2,560 mPa · s)

(Physical Property 3) Trimer Concentration Using the polyisocyanate obtained in each synthesis example as a sample, the gel permeation chromatograph measurement similar to the number average molecular weight measurement is performed, and the peak area% corresponding to the molecular weight three times that of diisocyanate is obtained. Trimer concentration was used.

(Physical Property 4) Dimer Concentration Using the polyisocyanate obtained in each synthesis example as a sample, the gel permeation chromatograph measurement similar to the number average molecular weight measurement is performed, and the peak area% corresponding to the molecular weight twice that of diisocyanate is obtained. Dimer concentration.

(Physical property 5) Allophanate group concentration with respect to isocyanurate group Using polyisocyanate obtained in each synthesis example as a sample, the concentration of allophanate group was determined by proton nuclear magnetic resonance ( ¹ H-NMR) by the following method. The polyisocyanate composition was dissolved in deuterium chloroform at a concentration of 10% by mass (0.03% by mass tetramethylsilane was added to the polyisocyanate composition). As a chemical shift standard, a hydrogen signal of tetramethylsilane was set to 0 ppm. Measured by ¹ H-NMR, signal of hydrogen atom bonded to nitrogen of allophanate group at around 8.5 ppm (1 mole of hydrogen atom per mole of allophanate group) and isocyanurate group at around 3.85 ppm The signal area ratio of the hydrogen atom of the methylene group adjacent to (6 mole of hydrogen atom per mole of isocyanurate group) was measured. The integrated value of the signal around 3.85 ppm was divided by the number of hydrogen atoms being measured (6), and from that value, the number of moles of all isocyanurate groups was taken as 100, and the number of moles of allophanate groups was shown. .
Device: JNM-ECS400, trade name of JEOL Ltd.
Resonance frequency: 400 MHz
Integration count: 128
Solvent: Deuterated chloroform Sample concentration: About 40 mg / mL

(Physical property 6) Concentration of isocyanate group (mass%)
Using the polyisocyanate obtained in each synthesis example as a sample, 1 to 3 g of the polyisocyanate produced in the production example was precisely weighed (Wg) in an Erlenmeyer flask, and then 20 mL of toluene was added to completely dissolve the polyisocyanate. Thereafter, 10 mL of a 2N di-n-butylamine toluene solution was added, thoroughly mixed, and allowed to stand at room temperature for 15 minutes. Furthermore, 70 mL of isopropyl alcohol was added to this solution and mixed thoroughly. This solution was titrated with a 1 N hydrochloric acid solution (factor F) using an indicator to obtain a titration value V2 mL. The same titration operation was performed without using polyisocyanate, and a titration value V1 mL was obtained. From the obtained titration value V2 mL and titration value V1 mL, the isocyanate group concentration of the polyisocyanate was calculated based on the following formula.
Isocyanate group concentration (mass%) = (V1-V2) × F × 42 / (W × 1000) × 100

(Physical property 7) Block polyisocyanate concentration After precisely weighing an aluminum dish having a bottom diameter of 38 mm, about 1 g of the block polyisocyanate composition obtained in Examples or Comparative Examples was precisely weighed on the aluminum dish (W1 ) After adjusting the block polyisocyanate composition to a uniform thickness, it was held in an oven at 105 ° C. for 1 hour. After the aluminum dish reached room temperature, the block polyisocyanate remaining in the aluminum dish was precisely weighed (W2).
Block polyisocyanate concentration (mass%) = W2 / W1 × 100

(Physical property 8) Effective isocyanate group content ratio With respect to the block polyisocyanate composition obtained in each Example or Comparative Example, the effective isocyanate group content ratio is the polyisocyanate charge amount, the isocyanate group content ratio, the blocking agent, and It calculated | required by calculation from the preparation amount of monool.

(Physical property 9) Mass concentration of dimer in which all isocyanate groups are blocked with a blocking agent The same as the number average molecular weight measurement of polyisocyanate using the block polyisocyanate composition obtained in each Example or Comparative Example as a sample The gel permeation chromatographic measurement of the blocked polyisocyanate composition was carried out, and all the isocyanate groups blocked the peak area% corresponding to the molecular weight obtained by adding the double molecular weight of the diisocyanate monomer and the double molecular weight of the blocking agent. It was shown as the mass concentration of the dimer blocked with the agent.

(Physical Property 10) Mass Concentration of Trimer in Which All Isocyanate Groups are Blocked with Blocking Agent Similar to the measurement of the number average molecular weight of polyisocyanate using the block polyisocyanate composition obtained in each Example or Comparative Example as a sample The gel permeation chromatographic measurement of the block polyisocyanate composition was carried out, and the peak area% corresponding to the molecular weight obtained by adding 3 times the molecular weight of the diisocyanate monomer and 3 times the molecular weight of the blocking agent was blocked by all isocyanate groups. The mass concentration of the trimer blocked by is shown.

(Physical property 11) Polymerization monoalcohol unit mass concentration in block polyisocyanate It calculated by the preparation ratio of the said polyisocyanate with respect to the block polyisocyanate composition obtained by each Example or the comparative example.

(Physical property 12) Concentration of allophanate group with respect to isocyanurate group in block polyisocyanate Using the block polyisocyanate composition obtained in each Example or Comparative Example as a sample, proton nuclear magnetic resonance similar to the measurement of physical properties of the above polyisocyanate Measurement was performed and the same calculation was performed.

(Evaluation 1) Compatibility Using the block polyisocyanate composition obtained in each example or comparative example as a sample, the block polyisocyanate concentration is 50% by mass in a 20 mL glass bottle at 23 ° C. Diluted with toluene to ensure complete compatibility. Thereafter, normal hexane was added in an amount of 10% by mass with respect to the total mass, the mass at the time of clouding was measured visually, and the percentage of the mass of normal hexane to the block polyisocyanate solution was calculated. The case where this value exceeds 100% was evaluated as 1 (good), 50 to 100% as 2 (somewhat good), and less than 50% as poor.

(Evaluation 2) Curability Using the block polyisocyanate composition obtained in each Example or Comparative Example as a sample, acrylic polyol “SETALUX1767” (manufactured by Nuplex), block polyisocyanate, and polyisocyanate composition for hydroxyl group of acrylic polyol. The coating composition was prepared by mixing the isocyanate groups at a molar ratio of 1.0 and adjusting the solid content to 50% by mass using n-butyl acetate. Using a bar coater, a coating composition was applied on a polypropylene plate to a dry film thickness of 40 μm, and this was left in an oven at 130 ° C. or 150 ° C. for 30 minutes, and then the coating film was peeled off. The mass was measured. This coating film (film) was immersed in acetone at 23 ° C. for 24 hours. After immersion, the coating film was dried at 80 ° C. for 60 minutes, and then its mass was measured. Curability was evaluated by the ratio of the mass after immersion to the mass before immersion (gel fraction:%). When the gel fraction exceeds 85%, the curability is good and expressed as “1”, and when the gel fraction is 75% or more and less than 85%, the curability is almost good and expressed as “2”. When the gel fraction was less than 75%, the curability was poor and represented as “3”.

(Synthesis Example 1)
A four-necked flask equipped with a stirrer, thermometer, reflux condenser, nitrogen blowing tube, and dropping funnel is placed in a nitrogen atmosphere, and 1000 parts by mass of HDI and 2.0 parts by mass of isobutanol are charged. Hold at 80 ° C. for 2 hours. Thereafter, the isocyanurate-forming catalyst tetramethylammonium capryate was added to carry out an isocyanurate-forming reaction. When the conversion rate reached 20%, phosphoric acid was added to stop the reaction. The reaction solution was further maintained at 160 ° C. for 1 hour. This heating produced uretdione group-containing polyisocyanate. The reaction solution was cooled, filtered, and unreacted HDI was removed using a thin film evaporator. The yield and physical property values of the resulting polyisocyanate are shown in Table 1.

(Synthesis Example 2)
The inside of a four-necked flask equipped with a stirrer, thermometer and condenser was replaced with nitrogen, charged with 1000 parts by mass of HDI, added tetramethylammonium caprate as a catalyst while stirring at 60 ° C., and the conversion rate was 20%. At that time, 0.2 g of phosphoric acid was added to stop the reaction. Then, after filtering a reaction liquid, the unreacted HDI monomer was removed with the thin film distillation apparatus. The yield and physical property values of the obtained polyisocyanate are shown in Table 1.

(Synthesis Example 3)
A four-necked flask equipped with a stirrer, thermometer, reflux condenser, nitrogen blowing tube, and dropping funnel was placed in a nitrogen atmosphere, 1000 parts by mass of HDI was charged, and the reactor internal temperature was maintained at 70 ° C. with stirring. The isocyanurate conversion catalyst tetramethylammonium capryate was added, and when the conversion reached 40%, phosphoric acid was added to stop the reaction. After the reaction solution was filtered, unreacted HDI was removed using a thin film evaporator. The yield and physical property values of the resulting polyisocyanate are shown in Table 1.

  In Table 1, “trimer concentration” indicates the mass concentration of the trimer compound composed of three molecules of the diisocyanate monomer in the polyisocyanate precursor, and “dimer concentration” indicates in the polyisocyanate precursor. 2 shows the mass concentration of a dimer compound composed of two diisocyanate monomers, and “allophanate / isocyanurate molar ratio” indicates the number of moles of allophanate groups when the number of isocyanurate groups is 100.

Example 1
In the same reactor as in Production Example 1, 49.7 parts by mass of the polyisocyanate obtained in Synthesis Example 1 and polypropylene glycol (trade name “Preminol SX1060”, molecular weight 600 of Asahi Glass Co., Ltd.), which is a hydroxyl group at one end, 16.5 masses Part, urethane catalyst (manufactured by Nitto Kasei Kogyo Co., Ltd., trade name “Neostan U-810”) was charged in an amount of 0.01 part by mass, and kept at 80 ° C. for 2 hours in a nitrogen atmosphere. Thereafter, 24.9 parts by mass of 3,5-dimethylpyrazole was added, and it was confirmed by infrared spectrum (manufactured by JASCO Corporation: product name FT / IR-4000) that there was no characteristic absorption of isocyanate groups. Then, 8.8 mass parts of dipropylene glycol monomethyl ether was added, and it hold | maintained for 30 minutes at 80 degreeC, and obtained the block polyisocyanate composition. The obtained block polyisocyanate had a mass concentration of 90% and an effective isocyanate group content of 11.5%. Table 2 shows the physical properties and evaluation results of the block polyisocyanate composition.

(Examples 2-3, Comparative Examples 1-7)
Various block polyisocyanate compositions were obtained in the same manner as in Example 1 except that the charged composition was changed to the composition described in Table 2. Table 2 shows the physical properties and evaluation results of the block polyisocyanate composition.

  In Table 2, “PPG (1)” represents a polymerized monoalcohol having a molecular weight of 600 (trade name “Preminol SX1060” from Asahi Glass Co., Ltd.) obtained by adding propylene oxide (polyethylene oxide) to monoalcohol, and “PPG (2 ) "Indicates a polymerized monoalcohol having a molecular weight of 340 (trade name" New Paul LB-65 "from Sanyo Chemical Co., Ltd.) obtained by adding polyethylene oxide to butanol, and" 2EH "is 2-ethylhexanol (non-polymerized monool). ), “Pz” represents 3,5-dimethylpyrazole, “DPM” represents dipropylene glycol monomethyl ether, and “M concentration” represents the polyalkylene oxide unit mass concentration (%) in the block polyisocyanate. ) (Figures in parentheses are non-polymerized monool unit mass concentrations (%)) "T concentration" indicates the mass concentration (%) of the trimer in which all isocyanate groups are blocked with a blocking agent, and "U concentration" indicates that all isocyanate groups are blocking agents. The mass concentration (%) of the dimer that is blocked is shown. “A molar ratio” is the allophanate / isocyanurate molar ratio in the blocked polyisocyanate (of allophanate groups when the isocyanurate group is defined as 100 moles). The “effective NCO concentration” indicates an effective isocyanate group content (%).

  Since the block polyisocyanate composition according to the present invention is highly compatible with a polyol and the curable composition containing the polyol has low-temperature curability, the article can be coated with a high appearance at a low temperature in a short time.

Claims (7)

A polyisocyanate obtained from one or two or more diisocyanates selected from the group consisting of aliphatic diisocyanates and alicyclic diisocyanates, a polyalkylene oxide represented by the following formula (1), and active hydrogen in the molecule A block polyisocyanate composition obtained from the block agent having one or more,
The concentration of the trimer in which all isocyanate groups are blocked with the blocking agent is 25% by mass or more and 50% by mass or less with respect to the total amount of the block polyisocyanate composition, and all the isocyanate groups are The block polyisocyanate composition whose density | concentration of the dimer blocked with the blocking agent is 1.0 mass% or more and 20 mass% or less.

(In formula (1), R ₁ represents a hydrocarbon group having 3 to 10 carbon atoms, and R ₂ represents a hydrocarbon group having 1 to 10 carbon atoms.)   The block polyisocyanate composition according to claim 1, wherein the polyalkylene oxide has a number average molecular weight of 300 or more and 2000 or less. The block polyisocyanate composition according to claim 1 or 2, wherein R ₁ in the formula (1) represents a propylene group.   The block polyisocyanate composition according to any one of claims 1 to 3, wherein the diisocyanate contains at least hexamethylene diisocyanate.   The block polyisocyanate composition according to any one of claims 1 to 4, wherein the blocking agent comprises at least 3,5-dimethylpyrazole.   A curable composition comprising at least the block polyisocyanate composition according to any one of claims 1 to 5.   An article comprising: an adherend; and a cured product obtained by curing the curable composition according to claim 6 covering the adherend.