JP6297395B2 - Polyisocyanate and curable composition - Google Patents

Description

  The present invention relates to polyisocyanates and curable compositions.

  Urethane coatings using polyisocyanate as a curing agent form a coating film excellent in durability and chemical resistance, and the demand for the coating is increasing year by year. Since the isocyanate group possessed by the polyisocyanate which is a curing agent reacts with the hydroxyl group of a polyol frequently used as a main agent at room temperature, the paint containing them is applied to various objects to be coated and has a wide range of applications. In recent years, such paints have been eagerly desired to shorten the time required to form a coating film and to improve curability at low temperatures from the viewpoint of energy saving and productivity improvement.

  In order to satisfy those demands, the present inventors have proposed a polyisocyanate having a high number of isocyanate average functional groups (average number of isocyanate groups) (see Patent Document 1).

JP-A-6-293878

  However, the polyisocyanate described in Patent Document 1 is a compound having two or more active hydrogens in the molecule that are reactive with isocyanate groups such as polyol as a main agent (hereinafter also referred to as “active hydrogen compound”). ) And the concealability of the base material are limited, and there is still room for improvement in these respects. Here, the “undercoating property of the base material” means a property of smoothing the unevenness of the portion that becomes the base when the curable composition containing polyisocyanate is applied (hereinafter also referred to as “underground concealing property”). .)

  The present invention has been made in view of the above circumstances, and is a polyisocyanate excellent in both curability by reaction with an active hydrogen compound and compatibility with the active hydrogen compound, and also has excellent base concealing properties, and It aims at providing the curable composition containing.

  As a result of intensive studies to solve the above problems, the present inventors have found that a polyisocyanate using both monoalcohol and polyol as raw materials can solve the above problems, and have completed the present invention.

That is, the present invention is as follows.
[1] 70 to 90% by mass of an aliphatic diisocyanate monomer unit, 5 to 20% by mass of a polyol unit, and 1.0 to 10% by mass of a monoacol unit with respect to the total amount of the polyisocyanate. 0.01 to 1% by weight of diisocyanate monomer,
Polyisocyanate having a viscosity at 25 ° C. of 3000 to 40000 mPa · s.
[2] The polyisocyanate according to [1], wherein the polyol is a polyester polyol.
[3] The polyisocyanate according to [2], wherein the polyester polyol is derived from ε-caprolactone.
[4] The polyisocyanate according to [1] or [2], wherein the polyol has an average number of hydroxyl groups of 3 to 4.
[5] The polyisocyanate according to any one of [1] to [4], wherein the monoalcohol has 4 to 10 carbon atoms.
[6] A curable composition comprising the polyisocyanate according to any one of [1] to [5].

  According to the present invention, both curability by reaction with an active hydrogen compound (hereinafter also simply referred to as “curability”) and compatibility with an active hydrogen compound (hereinafter also simply referred to as “compatibility”) are excellent. Furthermore, it is possible to provide a polyisocyanate having a good foundation hiding property and a curable composition containing the polyisocyanate.

  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 the following embodiment and is within a scope not departing from the gist thereof. Various modifications are possible. Further, “(meth) acryl” in the present specification means “acryl” and “methacryl” corresponding thereto.

[Polyisocyanate]
The polyisocyanate of the present embodiment is a polymer in which the raw material contains an aliphatic diisocyanate monomer, a monoalcohol, and a polyol, and the terminal functional group is an isocyanate group, an aliphatic diisocyanate monomer unit, a polyol unit, and a monoalcohol unit. And 0.01 to 1% by mass of a diisocyanate monomer.

(Diisocyanate monomer unit)
The polyisocyanate of this embodiment has an aliphatic diisocyanate monomer unit. By having an aliphatic diisocyanate monomer unit, the weather resistance of a coating film formed using this polyisocyanate tends to be improved.

  The “aliphatic diisocyanate monomer” used in the present embodiment refers to a diisocyanate compound having an aliphatic group in its structure and not having an aromatic group. Although it does not specifically limit as an aliphatic diisocyanate monomer, For example, a C4-C30 thing other than an isocyanate group is preferable, and a thing of 4-8 is more preferable. Such an aliphatic diisocyanate monomer is not particularly limited. For example, tetramethylene-1,4-diisocyanate, pentamethylene-1,5-diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethyl-hexamethylene- Examples include 1,6-diisocyanate and lysine diisocyanate. An aliphatic diisocyanate monomer may be used individually by 1 type, or may use 2 or more types together.

  Among these, the aliphatic diisocyanate monomer preferably contains hexamethylene diisocyanate (hereinafter also referred to as “HDI”). By including HDI, it tends to be able to form a coating film having better followability with respect to a substrate with large deformation.

  The polyisocyanate of this embodiment may have an alicyclic diisocyanate monomer unit in addition to the aliphatic diisocyanate monomer unit. The alicyclic diisocyanate monomer is a diisocyanate compound having a cyclic aliphatic group in its structure and no aromatic group. Although it does not specifically limit as an alicyclic diisocyanate monomer, For example, a C8-C30 thing is preferable. Such an alicyclic diisocyanate monomer is not particularly limited, and examples thereof include isophorone diisocyanate, 1,3-bis (isocyanatomethyl) -cyclohexane, and 4,4'-dicyclohexylmethane diisocyanate. An alicyclic diisocyanate monomer may be used individually by 1 type, or may use 2 or more types together.

  In the polyisocyanate of this embodiment, the isocyanate group of these diisocyanate monomers is selected from the group consisting of, for example, a biuret bond, a urea bond, an isocyanurate bond, a uretdione bond, a urethane bond, an allophanate bond, and an iminooxadiazine dione bond. Form one or more bonds. The bond may include two or more kinds of bonds such as an isocyanurate bond and an allophanate bond, and an isocyanurate bond and a uretdione bond. Among these, it is preferable that the isocyanate group forms an isocyanurate bond having heat resistance and an allophanate bond that promotes polyfunctionalization of the isocyanate group.

  The polyisocyanate having a biuret bond has a so-called biuretizing agent such as water, t-butanol or urea and a diisocyanate monomer in a molar ratio of (biuretizing agent) / (isocyanate group of diisocyanate monomer) of about 1/2 to about After making it react on the conditions used as 1/100, it can obtain by removing an unreacted diisocyanate monomer. These techniques are disclosed in, for example, JP-A Nos. 53-106797, 55-11452, and 59-95259.

  Polyisocyanates having urea linkages can be formed from isocyanate groups and water or amine groups. The content of urea bonds in the polyisocyanate is preferably small. Thereby, it exists in the tendency for the polyisocyanate obtained to become hard to aggregate.

  The polyisocyanate having an isocyanurate bond is subjected to an isocyanurate conversion reaction of a diisocyanate monomer with a catalyst or the like, for example, and the reaction is stopped when the conversion rate is about 5 to about 80% by mass, and an unreacted diisocyanate monomer is removed. It can be obtained by removing. At this time, it is preferable to use a compound having a hydroxyl group as a raw material. Examples of the compound having a hydroxyl group include the same compounds as those described later. When these compounds having a hydroxyl group are used as raw materials, the resulting polyisocyanate has an allophanate bond as well as an isocyanurate bond.

  The polyisocyanate having a uretdione bond can be obtained by using a uretdione-forming catalyst. These techniques are disclosed in, for example, Japanese Patent Application Laid-Open No. 2007-332133, Japanese Patent Application Laid-Open No. 2008-273788, Japanese Patent Application Laid-Open No. 2009-137961, and the like.

  The polyisocyanate having a urethane bond reacts with a hydroxyl group-containing compound and a diisocyanate monomer at an equivalent ratio of hydroxyl group to isocyanate group (hydroxyl group / isocyanate group) of about 1/2 to about 1/100, and then unreacted. This can be obtained by removing the diisocyanate monomer.

  The polyisocyanate having an iminooxadiazinedione bond is not particularly limited, and can be obtained using, for example, a catalyst. A technique related to this is disclosed in, for example, Japanese Patent Application Laid-Open No. 2004-534870.

  In the polyisocyanate of this embodiment, the mass concentration (content) of the aliphatic diisocyanate monomer unit is preferably 70 to 90% by mass, and more preferably 73 to 87% by mass. When the mass concentration of the aliphatic diisocyanate monomer unit is within such a range, the isocyanate group concentration of the polyisocyanate increases, and the crosslinking density of the resulting coating film tends to increase. Moreover, it exists in the tendency which can ensure high the isocyanate group average number of polyisocyanate because the said mass concentration is 90 mass% or less.

(Polyol unit)
Part of the polyisocyanate of this embodiment is composed of polyol units. A polyol unit means the part originating in the polyol which comprises a part of polyisocyanate. The hydroxyl group of the polyol reacts with the isocyanate group, but there is no leaving product during this reaction. Therefore, the charged polyol does not decrease in mass as a raw material and constitutes a part of the polyisocyanate.

  When the polyisocyanate has a polyol unit, the curability due to the reaction with the active hydrogen compound as the main component tends to be improved.

  The polyol used in the present embodiment is a compound having two or more hydroxyl groups in one molecule. The hydroxyl group of the polyol reacts with the isocyanate group of the diisocyanate monomer to form part of the polyisocyanate. The hydroxyl group and isocyanate group of the polyol form a urethane bond and an allophanate bond. When the polyisocyanate undergoes an isocyanuration reaction after the reaction between the hydroxyl group and the isocyanate group, the hydroxyl group and the isocyanate group form an allophanate bond. The number of hydroxyl groups in one molecule of polyol is preferably 3 to 4 from the viewpoint of further improving the curability.

  Polyols include polyols that have not undergone polymerization (hereinafter referred to as “polyhydric alcohol”) and polyols that have undergone polymerization.

  Among the polyhydric alcohols, the dihydric alcohol having two hydroxyl groups in one molecule is not particularly limited. For example, an ether bond is formed in a molecule such as diethylene glycol, triethylene glycol, dipropylene glycol and tripropylene glycol. Having; and ethylene 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-butanedi 2-ethyl-hexanediol, 1,2-octanediol, 1,2-decanediol, 2,2,4-trimethylpentanediol, 2-butyl-2-ethyl-1,3-propanediol, , 2-diethyl-1,3-propanediol, etc., which do not have an ether bond in the molecule.

  Although it does not specifically limit as a trihydric alcohol which has three hydroxyl groups in 1 molecule among polyhydric alcohols, For example, glycerol and a trimethylol propane are mentioned. Moreover, although it does not specifically limit as a tetrahydric alcohol which has four hydroxyl groups in 1 molecule, For example, a pentaerythritol is mentioned. Furthermore, although it does not specifically limit as a pentahydric alcohol which has five hydroxyl groups in 1 molecule, For example, glucose is mentioned. Furthermore, the hexavalent alcohol having 6 hydroxyl groups in one molecule is not particularly limited, and examples thereof include sorbitol.

  The polyol that has undergone polymerization history is not particularly limited, and examples thereof include polyester polyol, polyether polyol, (meth) acryl polyol, polyolefin polyol, and polycarbonate polyol.

  The polyester polyol is not particularly limited. For example, a polyester polyol obtained by a condensation reaction between a dibasic acid or a mixture of two or more thereof and a polyhydric alcohol or a mixture of two or more thereof, and a polyhydric alcohol are started. Examples of the compound include polycaprolactones obtained by ring-opening polymerization of ε-caprolactone. Although it does not specifically limit as said dibasic acid or its 2 or more types of mixture, For example, it is represented by succinic acid, adipic acid, sebacic acid, dimer acid, maleic anhydride, phthalic anhydride, isophthalic acid, and terephthalic acid. 1 type, or 2 or more types chosen from the group which consists of carboxylic acid is mentioned. Although it does not specifically limit as said polyhydric alcohol or its 2 or more types of mixture, For example, 1 type, or 2 or more types chosen from the group which consists of ethylene glycol, propylene glycol, diethylene glycol, neopentyl glycol, trimethylol propane, and glycerol Is mentioned.

  The polyether polyol is not particularly limited. For example, a polyhydric alcohol or a mixture of two or more thereof using a metal hydroxide, a strongly basic catalyst, a complex metal cyanide complex, or the like, an alkylene oxide or a mixture thereof. Polyether polyols obtained by random or block addition of a mixture of two or more species; polyether polyols obtained by reacting an alkylene oxide with a polyamine compound such as ethylenediamine; and acrylamide and the like using these polyether polyols as a medium. Examples include so-called polymer polyols obtained by polymerization.

  Although it does not specifically limit as said metal hydroxide, For example, the hydroxide of lithium, sodium, and potassium is mentioned. Although it does not specifically limit as said strong basic catalyst, For example, an alcoholate and an alkylamine are mentioned. Although it does not specifically limit as said composite metal cyanide complex, For example, a metal porphyrin and a hexacyanocobaltate zinc complex are mentioned. Although it does not specifically limit as said alkylene oxide or its 2 or more types of mixture, For example, a propylene oxide, a butylene oxide, a cyclohexene oxide, and a styrene oxide are mentioned.

  The polyhydric alcohol or a mixture of two or more thereof is not particularly limited, but in addition to the polyhydric alcohols exemplified above, non-saccharides, sugar alcohol compounds, monosaccharides, disaccharides, trisaccharides, and tetrasaccharides Can be mentioned.

  Although it does not specifically limit as said non-saccharide, For example, diglycerin, ditrimethylol propane, pentaerythritol, and dipentaerythritol are mentioned.

  The sugar alcohol compound is not particularly limited, and examples thereof include erythritol, D-threitol, L-arabinitol, ribitol, xylitol, sorbitol, mannitol, galactitol, and rhamnitol.

  Although it does not specifically limit as said monosaccharide, For example, arabinose, ribose, xylose, glucose, mannose, galactose, fructose, sorbose, rhamnose, fucose, and a ribose source are mentioned.

  The disaccharide is not particularly limited, and examples thereof include trehalose, sucrose, maltose, cellobiose, gentiobiose, lactose and melibiose.

  Although it does not specifically limit as said trisaccharide, For example, raffinose, a gentianose, and meletitose are mentioned.

  Although it does not specifically limit as said tetrasaccharide, For example, a stachyose is mentioned.

  Although it does not specifically limit as (meth) acryl polyol, For example, acrylic acid ester which has active hydrogen, such as 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate, or 2-hydroxyethyl methacrylate, etc. Examples thereof include (meth) acrylic polyols obtained by copolymerizing a methacrylic acid ester having active hydrogen and a (meth) acrylic acid ester such as methyl acrylate or ethyl methacrylate having no active hydrogen.

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

  Although it does not specifically limit as a polycarbonate polyol, For example, the polymer which superposed | polymerized carbonate ester, such as alkylene carbonate, such as ethylene carbonate, and dialkyl carbonate, such as diethyl carbonate, is mentioned.

  As the polyol, a polyol having undergone polymerization history is preferable, a polyester polyol is more preferable, and a polycaprolactone polyol obtained by ring-opening polymerization of ε-caprolactone is more preferable. In the polyol, the average number of hydroxyl groups per molecule is preferably 3-4. When the average number of hydroxyl groups is 3 to 4, a high average number of isocyanate groups can be obtained. Further, from the viewpoint of increasing the isocyanate group concentration of the polyisocyanate, the number average molecular weight of the polyol is preferably 200 to 1,000. The number average molecular weight of the polyol is measured according to the method described in the Examples below.

  The “average number of hydroxyl groups per molecule” is the number of hydroxyl groups that one statistical average molecule of polyol has, and is obtained from the number average molecular weight and the hydroxyl value.

  In the polyisocyanate of this embodiment, from the viewpoint of increasing the average number of isocyanate groups, it is preferable that the hydroxyl group of the polyol reacts with the isocyanate group to form an allophanate group.

  In the polyisocyanate of the present embodiment, the mass concentration (content) of the polyol unit is preferably 5 to 20% by mass, and more preferably 10 to 20% by mass. When the mass concentration of the polyol unit is within such a range, the curability of the curable composition containing polyisocyanate can be increased and the isocyanate group concentration can be increased.

(Monoalcohol unit)
Part of the polyisocyanate of this embodiment is composed of monoalcohol units. The monoalcohol unit refers to a part derived from monoalcohol constituting a part of polyisocyanate. The hydroxyl group of the monoalcohol reacts with the isocyanate group, but there is no leaving product during this reaction. Therefore, the monoalcohol charged as a raw material does not decrease in mass and constitutes a part of polyisocyanate.

  The monoalcohol is preferably a compound having an aliphatic group in its structure and no aromatic group. Such monoalcohol is not particularly limited, and for example, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-methyl-1-propanol, 2-butanol, 1-pentanol, 3-methyl- 1-butanol, 2-methyl-1-butanol, 2,2dimethyl-1-propanol, 2-pentanol, 3-methyl-2-butanol, 3-pentanol, 2-methyl-2-butanol, 1-hexanol 2-methyl-1-pentanol, 3-methyl-1-pentanol, 4-methyl-1-pentanol, 2,2-dimethyl-1-butanol, 2-ethyl-1-butanol, 2-hexanol 3-hexanol, 3-methyl-2-pentanol, 4-methyl-2-pentanol, 2-methyl-3-pentanol 3,3-dimethyl-2-butanol, 1-heptanol, 2-heptanol, 3-heptanol, 4-heptanol, 1-octanol, 6-methyl-1-heptanol, and 2-ethylhexanol. Monoalcohol is used alone or in combination of two or more.

  The monoalcohol preferably has 4 to 10 carbon atoms, and more preferably 4 to 8 carbon atoms. In addition, from the viewpoint of more effectively and reliably achieving the effects of the present invention, the monoalcohol is more preferably a primary alcohol, and further preferably has a branched structure.

  In the poisocyanate, the mass concentration (content) of the monoalcohol unit is 0.1 to 10% by mass, and preferably 0.1 to 7.5% by mass. When the mass concentration of the monoalcohol unit is 0.1% by mass or more, the compatibility of the polyisocyanate with the active hydrogen compound as the main component is improved, and when it is 10% by mass or less, the main component of the polyisocyanate is There is a tendency for the curability by reaction with a certain active hydrogen compound to increase,

  The hydroxyl group of the monoalcohol preferably reacts with an isocyanate group to form an allophanate bond.

  When the reaction is carried out under the condition that the isocyanate group is in a large excess amount compared with the hydroxyl group, generally, the hydroxyl group of the monoalcohol and the isocyanate group of the diisocyanate monomer react, and the average number of isocyanate groups of the polyisocyanate in which allophanate bonds are formed is 2. Therefore, the curability of the polyisocyanate containing this is low. Nevertheless, it is surprising that a polyisocyanate having high curability could be obtained even when such a monoalcohol was used as one of the raw materials.

  In the polyisocyanate of the present embodiment, the molar ratio of monoalcohol-derived allophanate bond and isocyanurate bond (monoalcohol-derived allophanate bond / isocyanurate bond) is preferably 2/98 to 60/40. It is more preferable that it is 97-50 / 50. When this molar ratio is within the above range, the compatibility of the polyisocyanate with the active hydrogen compound as the main agent and the underlying concealability are further improved.

  The molar ratio (total allophanate bond / isocyanurate bond) of all allophanate bonds and isocyanurate bonds in the polyisocyanate when both polyol and monoalcohol are used as raw materials is preferably 75/25 to 50/50. . When this molar ratio is within the above range, there is an advantage that the curability and the weather resistance of the coating film obtained thereby are further improved.

(Viscosity of polyisocyanate)
The viscosity of the polyisocyanate of the present embodiment is preferably 3000 to 40000 mPa · s, more preferably 3000 to 30000 mPa · s at 25 ° C. When this viscosity is 3000 mPa · s or more, the curability tends to be further improved, and when it is 40000 mPa · s or less, the compatibility tends to be better. The viscosity of the polyisocyanate is surprisingly reduced unexpectedly as the monoalcohol forms part of the polyisocyanate. This is considered to be excellent both in curability by the reaction of the polyisocyanate with the active hydrogen compound and in compatibility with the active hydrogen compound.

(Isocyanate group mass concentration of polyisocyanate)
The isocyanate group mass concentration of the polyisocyanate of the present embodiment is preferably 10 to 23%, more preferably 15 to 22%. Here, the “isocyanate group mass concentration” is the mass concentration of the isocyanate group (formula weight 42) of the polyisocyanate. When the mass concentration is within the above range, there is an effect that the durability of the coating film obtained thereby is further improved.

(Mass concentration of polymer component)
The polyisocyanate of this embodiment can be obtained by performing a polymerization reaction using a diisocyanate monomer as a main raw material. This polymerization reaction is stopped at the stage where the diisocyanate monomer is present, and then the unreacted diisocyanate monomer is removed to obtain polyisocyanate. As the polymerization reaction proceeds, the molecular weight of the polyisocyanate increases and the polyisocyanate has a molecular weight distribution. When the polymerization reaction by the isocyanuration reaction is performed, the lowest molecular weight component is a trimer formed by three molecules of diisocyanate monomer. Further, a pentamer is formed from this trimer and two diisocyanate monomers.

  In the polyisocyanate of the present embodiment, the mass concentration (content) of a component having a molecular weight higher than the molecular weight corresponding to the pentamer of the diisocyanate monomer (hereinafter referred to as “polymer component having a molecular weight equal to or higher than the isocyanate pentamer”). ) Is preferably 50 to 90% by mass, more preferably 60 to 90% by mass, and still more preferably 60 to 80% by mass. When this mass concentration is 50% by mass or more, the curability of the polyisocyanate tends to be further improved, and when it is 90% by mass or less, the compatibility tends to be better.

(Diisocyanate monomer concentration)
The polyisocyanate of this embodiment is obtained by stopping the polymerization in the state where the unreacted diisocyanate monomer is present, and then removing the unreacted diisocyanate monomer. Therefore, a trace amount of unreacted diisocyanate monomer is present in the obtained polyisocyanate. The mass concentration (content) of the unreacted diisocyanate monomer is 0.01 to 1% by mass, preferably 0.01 to 0.5% by mass, and 0.01 to 0.3% by mass. More preferably it is. When this mass concentration is 0.01% by mass or more, economic productivity is good, and when it is 1% by mass or less, curability tends to be good.

(Production of polyisocyanate)
Next, the manufacturing method of the polyisocyanate of this embodiment is explained in full detail.

  As the polyisocyanate raw material, at least a diisocyanate monomer, a polyol and a monoalcohol are used. A preferred reaction form in the production of the polyisocyanate is an isocyanuration reaction. The isocyanurate reaction is a reaction in which an isocyanurate bond is formed from three isocyanate groups. By the isocyanuration reaction, the urethane bond formed from the isocyanate group and the hydroxyl group of the polyol and monoalcohol further reacts with the isocyanate group to form an allophanate bond.

  The reaction between the isocyanate group of the diisocyanate monomer and the hydroxyl group of the polyol and monoalcohol can be carried out before the isocyanuration reaction or simultaneously with the isocyanuration reaction. Of these, it is preferable to perform the reaction before the isocyanuration reaction because the heat of reaction can be easily removed.

  The isocyanurate formation reaction is performed using, for example, a catalyst, and when the predetermined conversion rate is reached, the reaction is stopped and the diisocyanate monomer is removed to obtain a polyisocyanate. As the catalyst for the isocyanuration reaction used in this case, those having basicity are generally preferred. Specifically, (a) a tetraalkylammonium hydroxide such as tetramethylammonium or tetraethylammonium, and an organic such as acetic acid. Salts of weak acids, (b) hydroxyalkylammonium hydroxides such as trimethylhydroxypropylammonium, trimethylhydroxyethylammonium, triethylhydroxypropylammonium or triethylhydroxyethylammonium, and salts of weak organic acids such as acetic acid, (c) acetic acid, octyl Alkali metal salts such as tin, zinc or lead of alkyl carboxylic acids such as acid, capric acid or myristic acid, (d) metal alcoholates such as sodium or potassium, (e) hexamethyl Aminosilyl group-containing compound such as silazane, (f) Mannich bases, (g) in combination with tertiary amines with epoxy compounds, as well, include phosphorus-based compounds such as (h) tributylphosphine. It is preferable that the usage-amount of these catalysts is selected from the range of 10 ppm-1 mass% with respect to the total mass of the diisocyanate, polyol, and monoalcohol which are raw materials. In order to terminate the reaction, these catalysts may be neutralized by adding an acidic substance such as phosphoric acid or acidic phosphate ester, or deactivated by thermal decomposition or chemical decomposition.

  The yield of polyisocyanate is preferably 10 to 70% by mass. When the yield is 70% by mass or less, the viscosity of the polyisocyanate tends to be lowered. Here, a yield means the ratio of the mass of the obtained polyisocyanate with respect to the mass of all the raw materials used at the time of polyisocyanate manufacture.

  The reaction temperature in the isocyanuration reaction is preferably 20 ° C. or higher from the viewpoint of further increasing the reactivity, and preferably 200 ° C. or lower from the viewpoint of further suppressing product coloring and occurrence of side reactions. This reaction temperature is more preferably 50 to 150 ° C.

  After completion of the reaction, unreacted diisocyanate monomer is removed by a thin film evaporator, extraction or the like to obtain polyisocyanate.

(Allophanate bond and isocyanurate bond)
The polyisocyanate of this embodiment preferably has both an isocyanurate bond and an allophanate bond. The molar ratio of monoalcohol-derived allophanate bond to isocyanurate bond (monoalcohol-derived allophanate bond / isocyanurate bond) is preferably 2/98 to 60/40, and 3/97 to 50/50. More preferred. When this molar ratio is in the range of 2/98 to 60/40, it is possible to further improve the compatibility of the polyisocyanate with the active hydrogen compound as the main component and the underlying concealing property.

(Average number of isocyanate groups in polyisocyanate)
The average number of isocyanate groups in the polyisocyanate is the number of isocyanate groups that one statistical average molecule of the polyisocyanate has, and is derived based on the method described in the following examples.

  The average number of isocyanate groups in the polyisocyanate of the present embodiment is preferably 3.5 or more and 15 or less, and more preferably 3.5 or more and 10 or less. When the average number of isocyanate groups is 3.5 or more, the curability tends to be more excellent. Further, when the average number of isocyanate groups is 15 or less, the compatibility tends to be further improved. The average number of isocyanate groups greatly affects the curability of the polyisocyanate due to the reaction with the active hydrogen compound as the main component. In general, the polyisocyanate having a high average number of isocyanate groups has high curability. We have previously disclosed polyisocyanates having a high average number of isocyanate groups. On the other hand, the polyisocyanate of the present embodiment can exhibit the same high curability even though it has a lower average number of isocyanate groups than the polyisocyanate previously disclosed by the present inventors. This is surprising.

(Mass concentration of polymer component)
The polyisocyanate of the present embodiment has a molecular weight distribution, and in the polyisocyanate, the mass concentration (content) of the polymer component having a molecular weight equal to or higher than the isocyanate pentamer is preferably 50 to 90%, 60 to More preferably, it is 80 mass%. When this mass concentration is in the range of 50 to 90% by mass, both compatibility and curability become better. The molecular weight of the diisocyanate monomer pentamer is five times that of the diisocyanate monomer.

(Block polyisocyanate)
The polyisocyanate of this embodiment may be a blocked polyisocyanate whose isocyanate group is blocked with a blocking agent.

  Here, the “blocking agent” refers to a compound that reacts with an isocyanate group and volatilizes at least 1 part by heating. The term “block” means that an isocyanate group is blocked with a blocking agent.

  Although it does not specifically limit as a blocking agent, For example, methanol, ethanol, 2-propanol, n-butanol, sec-butanol, 2-ethyl-1-hexanol, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol Alcohols such as 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, Monoalkylphenols such as n-hexylphenol, 2-ethylhexylphenol, n-octylphenol, n-nonylphenol, di-n-propylphenol, diisopropylphenol, isopropylcresol, di alkylphenols such as dialkylphenol such as n-butylphenol, di-t-butylphenol, di-sec-butylphenol, di-n-octylphenol, di-2-ethylhexylphenol, di-n-nonylphenol; phenol, cresol, ethylphenol, Phenols such as styrenated phenol and hydroxybenzoate; for example, active methylenes such as dimethyl malonate, diethyl malonate, methyl acetoacetate, ethyl acetoacetate and acetylacetone; mercaptans such as butyl mercaptan and dodecyl mercaptan; urea, Ureas such as thiourea and ethyleneurea; acid imides such as succinimide and maleic imide; formaldoxime, acetoaldoxime, acetoxime, methyl ethyl keto Oximes such as shim and cyclohexanone oxime; amines such as diphenylamine, aniline, carbazole, di-n-propylamine, diisopropylamine and isopropylethylamine; pyrazoles such as pyrazole, 3-methylpyrazole and 3,5-dimethylpyrazole; imidazole Imidazoles such as 2-methylimidazole; triazoles such as 1,2,4-triazole; imines such as ethyleneimine and polyethyleneimine; acetanilide, acetic acid amide, ε-caprolactam, δ-valerolactam, γ-butyrolactam, etc. Of the acid amides.

(Curable composition)
The curable composition of this embodiment preferably contains a polyisocyanate and an active hydrogen compound as main components. It is surprising that such a curable composition has good base concealment. Usually, when the viscosity of the polyisocyanate is high or the curability is high, the base concealability is poor. This is because when the viscosity of the resin component of the curable composition is high, the flowability of the resin is low, it takes time to conceal the unevenness, and the coating film surface is fixed during the concealment. In addition, even if the viscosity of the resin component is low, if the curability is high, curing starts before concealing the underlying irregularities, resulting in a decrease in resin fluidity. Fixed. On the other hand, although the polyisocyanate of this embodiment has high curability and high viscosity, the base concealability is good.

  The isocyanate group of the polyisocyanate can react with the active hydrogen of the active hydrogen compound to form, for example, a crosslinked coating film. Examples of the active hydrogen compound include polyols, polyamines, and polythiols. Among these, polyols are preferable from the viewpoint of versatility. Examples of this polyol include polyester polyol, polyether polyol, (meth) acryl polyol, polyolefin polyol, and fluorine polyol.

  Examples of the polyester polyol include dibasic acids selected from the group of carboxylic acids such as succinic acid, adipic acid, sebacic acid, dimer acid, maleic anhydride, phthalic anhydride, isophthalic acid and terephthalic acid, or two or more thereof. A polyester polyol obtained by a condensation reaction of a mixture of the above and a compound selected from the group of polyhydric alcohols such as ethylene glycol, propylene glycol, diethylene glycol, neopentyl glycol, trimethylolpropane and glycerin or a mixture of two or more thereof; In addition, for example, polycaprolactones obtained by ring-opening polymerization using ε-caprolactone and a polyhydric alcohol can be mentioned. These polyester polyols can be modified with aromatic diisocyanates, aliphatic diisocyanates and alicyclic diisocyanates and polyisocyanates obtained therefrom. In this case, in particular, aliphatic or alicyclic diisocyanates and the resulting polyisocyanates are preferred from the viewpoints of weather resistance and yellowing resistance.

  Examples of the polyether polyol include polyhydric alcohol or a mixture of two or more thereof, for example, hydroxide such as lithium, sodium or potassium, strong basic catalyst such as alcoholate or alkylamine, metal porphyrin, or hexacyano. Obtained by random or block addition of alkylene oxides such as ethylene oxide, propylene oxide, butylene oxide, cyclohexene oxide, styrene oxide or a mixture of two or more thereof using a complex metal cyanide complex such as zinc cobaltate complex. Polyether polyols obtained by reacting an alkylene oxide with a polyamine compound such as ethylene diamines; and these polyether polyols as a medium Obtained by polymerizing acrylamide Te, so-called polymer polyols and the like. Specific examples of the polyhydric alcohol used here include the above polyhydric alcohols.

  Examples of (meth) acrylic polyols include acrylic acid-2-hydroxyethyl, acrylic acid-2-hydroxypropyl, acrylic acid-2-hydroxybutyl, acrylic acid monoester of glycerin, and acrylic acid monoester of trimethylolpropane. Acrylic acid esters having a hydroxyl group such as methyl acrylate, ethyl acrylate, isopropyl acrylate, acrylic acid-n-butyl and acrylic acid ester having no hydroxyl group such as methacrylic acid-2 -Hydroxyethyl, methacrylic acid-2-hydroxypropyl, methacrylic acid-2-hydroxybutyl, methacrylic acid-3-hydroxypropyl, methacrylic acid-4-hydroxybutyl, methacrylic acid monoester of glycerin, and trimethyl Methacrylic acid esters having a hydroxyl group, such as methacrylic acid monoester of propane propane; methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, -n-butyl methacrylate, isobutyl methacrylate, n-hexyl methacrylate, lauryl methacrylate, etc. Methacrylic acid esters having no hydroxyl group; 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, Among compounds selected from the group consisting of other polymerizable monomers such as styrene, vinyl toluene, vinyl acetate, acrylonitrile and dibutyl fumarate, at least one polymerizable monomer having a hydroxyl group is essential. And, the polymerizable monomer alone or optionally include acrylic polyols obtained by polymerizing with other polymerizable monomers one or more.

  Examples of the polyolefin polyol include polybutadiene having two or more hydroxyl groups, hydrogenated polybutadiene, polyisoprene, and hydrogenated polyisoprene.

  The fluorine polyol is a polyol having a fluorine atom in the molecule. For example, fluoroolefins, cyclovinyl ethers, hydroxyalkyl vinyl ethers and monoolefins disclosed in JP-A-57-34107 and JP-A-61-275111. Examples thereof include copolymers such as carboxylic acid vinyl esters.

  The polyol may have a hydroxyl value of 30 to 200 mg KOH / g and an acid value of 0 to 30 mg KOH / g.

  Of these, preferred polyols are (meth) acrylic polyols and polyester polyols.

  Moreover, the curable composition of this embodiment may contain various solvents and additives depending on applications and purposes. Examples of the solvent include ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, esters such as ethyl acetate, n-butyl acetate and cellosolve acetate, and alcohols such as butanol and isopropyl alcohol. And it can select and use suitably according to a use. These solvents may be used alone or in combination of two or more.

  In addition, the curable composition of the present embodiment is optionally provided with an antioxidant such as hindered phenol, an ultraviolet absorber such as benzotriazole and benzophenone, such as titanium oxide, carbon black, indigo, quinacridone and pearl. You may contain pigments, such as mica, metal powder pigments, such as aluminum, and rheology control agents, such as a hydroxyethyl cellulose, a urea compound, and a microgel.

  In the curable composition of the present embodiment, the equivalent ratio of the isocyanate group of the polyisocyanate and the active hydrogen of the active hydrogen compound (isocyanate group / active hydrogen) is preferably 0.5 to 1.5, 0.8 It is more preferable that it is -1.2. When this equivalent ratio is within the above range, an effect that the durability of the coating film formed thereby is further enhanced is exhibited.

  The curable composition of the present embodiment can be applied to a material such as a steel plate or a surface-treated steel plate such as metal and plastic or inorganic material by, for example, roll coating, curtain flow coating, spray coating, electrostatic coating or bell coating. Alternatively, it is useful for imparting cosmetics, weather resistance, acid resistance, rust resistance, chipping resistance, etc. to pre-coated metal or automobile paint containing a rust-proof steel plate as a top intermediate coating. Moreover, the polyisocyanate of this embodiment is useful also as urethane raw materials, such as an adhesive agent, an adhesive, an elastomer, a foam, and a surface treating agent.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. The present invention is not limited in any way by the following examples.

(Measurement of number average molecular weight)
The number average molecular weight was determined as a polystyrene-based number average molecular weight by gel permeation chromatography (hereinafter referred to as “GPC”) using the following apparatus.
Apparatus: Tosoh Corporation HLC-802A
Column: Tosoh Corporation G1000HXL x 1
G2000HXL x 1
G3000HXL x 1 Carrier: Tetrahydrofuran Detection method: Differential refractometer

(Measurement of diisocyanate monomer content)
The content of the diisocyanate monomer, as represented by the following formula, is the peak area of the polyisocyanate peak obtained by the above GPC measurement and the peak area of the molecular weight corresponding to the diisocyanate monomer (for example, 168 for hexamethylene diisocyanate). And calculated from
(Diisocyanate monomer content) = (Diisocyanate monomer peak area) / {(Polyisocyanate peak area) + (Diisocyanate monomer peak area)} × 100

(Mass concentration of high molecular weight component equal to or higher than isocyanate pentamer equivalent molecular weight)
The mass concentration of the high molecular weight component equal to or higher than the molecular weight equivalent to the isocyanate pentamer is the total peak of the polyisocyanate in the total peak area of the high molecular weight component equal to or higher than the molecular weight of the diisocyanate monomer pentamer (840 if the diisocyanate monomer is HDI). It is a ratio with respect to the total area, and was obtained from the above GPC results.

(Measurement of isocyanate group concentration of polyisocyanate)
Into an Erlenmeyer flask, 1 to 3 g of polyisocyanate was precisely weighed (Wg), 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, and after thorough mixing, the mixture was allowed to stand at room temperature for 15 minutes. Furthermore, 70 mL of isopropyl alcohol was added to this solution and mixed well. The obtained liquid was titrated with a 1N hydrochloric acid solution (factor F) to an indicator. The titration value was V2 mL. Moreover, the same operation was performed when there was no precursor polyisocyanate, and this titration value was set to V1mL. From these titration values, the isocyanate group concentration of the polyisocyanate was calculated by the following formula.
Isocyanate group concentration (%) = (V1-V2) × F × 42 / (W × 1000) × 100

(Measurement of average number of isocyanate groups in polyisocyanate)
The average number of isocyanate groups in the polyisocyanate was determined from the following formula from the isocyanate group concentration and the number average molecular weight of the polyisocyanate.
Isocyanate group average number = number average molecular weight × isocyanate group concentration / 100/42

(Mass concentration of diisocyanate unit, polyol unit and monoalcohol unit)
These can be calculated from the mass of the charged raw material during the production of the polyisocyanate and the mass of the obtained polyisocyanate, and can also be calculated from the analysis of the polyisocyanate. In this example, the calculation was made from the analysis of the polyisocyanate.

In the analysis, proton nuclear magnetic resonance was measured, and the integrated value of the specific absorption peak was measured and calculated. The measurement conditions were as follows.
Device: JNM-ECS400, trade name of JEOL Ltd.
Measurement condition:
Resonance frequency: 400 MHz
Integration count: 128
Solvent: Deuterated chloroform Sample concentration: About 40 mg / mL

(Molar ratio of allophanate bond derived from hydroxyl group of monoalcohol and isocyanurate bond)
From the measurement result of the above proton nuclear magnetic resonance, the molar ratio of the allophanate bond and isocyanurate bond derived from the hydroxyl group of the monoalcohol was calculated. Monoalcohol was identified from the characteristic absorption of its alkyl group.

(viscosity)
The viscosity of the polyisocyanate was determined by using an E-type viscometer (manufactured by Tokimec, product name “VISCONIC RE-85U type”) with a rotor of 3 ° × R14 and the number of rotations according to the viscosity (described in the instruction manual). For example, in the range of 5000 to 10000 mPa · s, the rotation speed was 50 rpm) and the measurement was performed at 25 ° C.

(Evaluation of curability)
The curable composition was applied onto a polypropylene plate, and this was left in an oven at 80 ° C. for 30 minutes, and then the coating film was peeled off and 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 judged to be good and expressed as “1”, and when the gel fraction is 75% or more and less than 85%, the curability is judged to be almost satisfactory. When the gel fraction was less than 75%, the curability was judged to be poor and represented as “3”.

(Compatibility evaluation)
The curable composition was applied onto a 1 mm thick glass plate so that the film thickness of the coating film was 40 μm. After leaving still for 30 minutes at room temperature, it left still for 30 minutes in 80 degreeC oven. Then, after cooling and confirming that the coating film became 23 degreeC, the haze was measured using the following measuring apparatus. When the transparency of the coating film is high, the haze value is small, and it can be determined that the compatibility between the active hydrogen compound and the polyisocyanate is good.
Device name: Suga Test Instruments Co., Ltd. Haze meter, machine number “HGM2DP”

  When the haze value is less than 6, it is judged that the compatibility is good and expressed as “1”, and when it is 6 to 10, it is judged that the compatibility is almost good and expressed as “2”. In the case of being over, it was judged that the compatibility was poor and expressed as “3”.

(Evaluation of surface concealment)
A curable composition having the same composition as the Examples and Comparative Examples, except that the solid content of the resin was adjusted to 50% by adjusting the solvent on the cationic electrodeposition coating plate (black) of Standard Testpiece Co., Ltd. It was applied by an applicator so that the resin film thickness was 40 μm. After application, the mixture was allowed to stand at room temperature for 30 minutes, and then left in an oven at 80 ° C. for 30 minutes. Then, after cooling and confirming that the coating film became 23 degreeC, arithmetic mean roughness Ra value was measured on condition of the following using the following apparatus. It shows that base concealment property is so favorable that this Ra value is small.
Measuring apparatus: scanning white interference microscope manufactured by Zygo, trade name “NewView600s”
Magnification: 2.5 times Measurement method: Ra value is measured (arithmetic deviation from the center line)

  When the Ra value is 0.025 μm or less, it is judged that the background concealment is good and is expressed as “1”, and when it is more than 0.025 μm and 0.04 μm or less, the base concealability is substantially good. It was judged as “2”, and when it was over 0.04 μm, it was judged that the underlying concealability was poor and represented as “3”.

[Example 1]
[Production of polyisocyanate]
A four-necked flask equipped with a stirrer, thermometer, reflux condenser, nitrogen blowing tube, and dropping funnel was placed in a nitrogen atmosphere, and 1000 g of hexamethylene diisocyanate (hereinafter also referred to as “HDI”), trifunctional polyol (hydroxyl group) An average number of 3) polycaprolactone-based polyester triol (“Placcel 303”, trade name, manufactured by Daicel Corporation, molecular weight 300) 100 g and 2-ethylhexanol 30 g were charged, and the temperature in the reactor (urethanization temperature) was stirred. Was kept at 90 ° C. for 1 hour. Thereafter, the temperature in the reactor (nulation temperature) is maintained at 80 ° C., tetramethylammonium capriate as an isocyanurate reaction catalyst is added, and phosphoric acid is added when the yield reaches 50%. The reaction was stopped. After filtering the obtained reaction liquid, unreacted HDI was removed using a thin film evaporator to obtain the polyisocyanate of Example 1. About the obtained polyisocyanate, the mass concentration of the high molecular weight component equal to or higher than the molecular weight equivalent to the isocyanate pentamer is 64% by mass, the mass concentration of the diisocyanate monomer unit is 77% by mass, the mass concentration of the polyol unit is 18% by mass, 2-ethyl The mass concentration of the hexanol unit is 5.3% by mass, the mass concentration of the diisocyanate monomer is 0.1% by mass, the viscosity at 25 ° C. is 7300 mPa · s, the isocyanate group concentration is 18.2% by mass, the number average molecular weight is 1030, isocyanate. The group average number was 4.5.

[Examples 2 to 4, Comparative Examples 1 to 4)
[Production of polyisocyanate]
A polyisocyanate was obtained in the same manner as in Example 1 except that the atmosphere in the four-necked flask of the same apparatus as in Example 1 was changed to a nitrogen atmosphere and the raw materials and reaction conditions were changed as shown in Table 1. Table 1 shows the results of various characteristics of the polyisocyanate.

  In Table 1, “Di” represents a diisocyanate monomer, “PCL303” represents a trade name of a polycaprolactone-based polyester polyol (manufactured by Daicel Corporation, trifunctional polyol, number average molecular weight 300), and “2EHOH” “PLC410” indicates a trade name of polycaprolactone-based polyester polyol (manufactured by Daicel Corporation, tetrafunctional polyol (hydroxyl group average number 4), number average molecular weight 1000), and “pentamer or more”. Represents the mass concentration (mass%) of a high molecular weight component equal to or higher than the molecular weight equivalent to the isocyanate pentamer, "Di unit concentration" represents the mass concentration (mass%) of the diisocyanate monomer unit, and "POH concentration" represents the mass of the polyol unit. Concentration (% by mass), “Mono OH concentration” The amount concentration (mass%) is indicated, “monomer concentration” indicates the mass concentration (mass%) of the diisocyanate monomer, “NCO%” indicates the mass concentration (mass%) of the isocyanate group, and “Mn” is the number average molecular weight. “NCO average number” indicates the average number of isocyanate groups, and “mono / iso” indicates the molar ratio of monoalcohol-derived allophanate bonds to isocyanurate bonds.

Example 5
[Preparation and evaluation of curable composition]
Two kinds of acrylic polyols (trade name “Acridic A801” manufactured by DIC Corporation (solid content 50%, resin hydroxyl value 100 mg KOH / g), and product name “Setalux 1767” manufactured by Nuplex (solid content 65%, hydroxyl group concentration 4) 0.5%)) was mixed so that the mass ratio of the resin was 5: 5. The obtained mixture and the polyisocyanate obtained in Example 1 were mixed so that the equivalent ratio of the hydroxyl group of the mixture to the isocyanate group of the polyisocyanate was 1.0. Then, it diluted with butyl acetate so that the mass concentration of the resin component might be 50%, and the curable composition was obtained. About this curable composition, sclerosis | hardenability, compatibility, and base concealment property were evaluated. The results are shown in Table 2. The case where the score was 2 and 3 was judged as a good result.

[Examples 6-8, Comparative Examples 5-8]
A curable composition was obtained in the same manner as in Example 5 except that the type of polyisocyanate was changed as shown in Table 2. About these curable compositions, sclerosis | hardenability, compatibility, and base concealment property were evaluated. The results are shown in Table 2.

  The polyisocyanate of the present invention is useful as a raw material for urethane such as adhesives, pressure-sensitive adhesives, elastomers, foams and surface treatment agents, and has industrial applicability in these fields.

Claims (6)

70 to 90% by weight of aliphatic diisocyanate monomer units, 5 to 20% by weight of polyol units, and 1.0 to 10% by weight of monoalcohol units, based on the total amount of polyisocyanate, 0 Containing 0.01 to 1% by weight of diisocyanate monomer,
Polyisocyanate having a viscosity at 25 ° C. of 3000 to 40000 mPa · s.   The polyisocyanate according to claim 1, wherein the polyol is a polyester polyol.   The polyisocyanate according to claim 2, wherein the polyester polyol is derived from ε-caprolactone.   The polyisocyanate according to claim 1 or 2, wherein the polyol has an average hydroxyl group number of 3-4.   The polyisocyanate according to any one of claims 1 to 4, wherein the monoalcohol has 4 to 10 carbon atoms.   The curable composition containing the polyisocyanate of any one of Claims 1-5.