JP2013224350A - Polyisocyanate composition and paint composition containing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyisocyanate composition which retains high crosslinking property, has a low viscosity, ensures low occurrence of a diisocyanate monomer during the storage of the polyisocyanate, and develops high paint film hardness and excellent paint film smoothness when used as a curing agent, and a paint composition using the same as a curing agent.SOLUTION: A polyisocyanate composition is derived from an aliphatic diisocyanate monomer and an alcohol and satisfies all of the following conditions in a state where any solvent is not contained; (1) the concentration of an isocyanurate trimer: 55-95 mass%, (2) the molar ratio of allophanate groups/isocyanurate groups: 5-50%, (3) the molar ratio of urethodione groups/isocyanurate groups: 15-50%, (4) the molar ratio of [(allophanate groups+urethodione groups)/(isocyanurate groups)]: 20-100%, (5) the average number of isocyanate groups: 2.5-3.5, (6) the concentration of a diisocyanate monomer: ≤1 mass%, (7) the viscosity at 25°C: 150-700 mPa s, (8) the concentration of isocyanate groups: 22.0-25.0 mass%.

Description

  The present invention relates to a polyisocyanate composition and a coating composition using the same as a curing agent.

  Conventionally, urethane coatings formed from polyurethane paints have very excellent flexibility, chemical resistance, and stain resistance, and in particular aliphatic diisocyanates such as hexamethylene diisocyanate (hereinafter also referred to as HDI). The coating film using non-yellowing polyisocyanate derived from the above as a curing agent is further excellent in weather resistance, and its demand is increasing.

  2. Description of the Related Art In recent years, technological development for reducing the viscosity of polyisocyanates used as curing agents has been actively carried out due to an increase in global environmental protection. It is because the usage-amount of the organic solvent used for a coating composition can be reduced by making polyisocyanate low viscosity (patent document 1).

  On the other hand, a technique for reducing the viscosity of various polyisocyanates derived from HDI or the like is disclosed. One of such techniques is a polyisocyanate having a low viscosity uretdione group (Patent Document 2). This technique has resulted in a low viscosity polyisocyanate, but has low crosslinkability and may increase the diisocyanate monomer concentration during storage of the polyisocyanate, limiting its use. Moreover, the polyisocyanate containing only the uretdione group has a statistical average number of isocyanate groups (hereinafter referred to as an isocyanate group average number) of one polyisocyanate of 2 regardless of the molecular weight, and is poor in crosslinkability. There was also a problem.

  On the other hand, an isocyanurate group-containing polyisocyanate and an allophanate group-containing polysynthesized from an aliphatic monoalcohol having 6 to 9 carbon atoms and hexamethylene diisocyanate alone or a mixture of an aliphatic monoalcohol hexamethylene diisocyanate and isophorone diisocyanate having 6 to 9 carbon atoms. A mixture of isocyanates is disclosed (Patent Document 3). However, when the allophanate group / isocyanurate group molar ratio is high, a low-viscosity polyisocyanate is obtained. However, due to the influence of the monoalcohol used, the coating film hardness may be too low when used as a curing agent. It was.

Moreover, an isocyanurate group-containing polyisocyanate composition containing an allophanate group and a uretdione dimer in a specific ratio is disclosed (Patent Document 4). However, when a high level of coating film smoothness is considered, the coating film smoothness may not be expressed.
Thus, polyisocyanates that maintain high crosslinkability, have low viscosity, are excellent in storage stability, and exhibit high film hardness and excellent film smoothness when used as a curing agent have been desired.

Japanese Patent Publication No. 05-222007 Japanese Patent No. 3055197 Patent No. 3137201 International Publication No. 2007/046470 Pamphlet

  The present invention maintains high crosslinkability, low viscosity, low generation of diisocyanate monomer when polyisocyanate is stored, and provides high coating hardness and excellent coating smoothness when used as a curing agent. It aims at providing the polyisocyanate composition which expresses, and the coating composition which used this as a hardening | curing agent.

As a result of intensive studies, the present inventor has achieved the above-described problems with a specific polyisocyanate, and has reached the present invention.
That is, the present invention is as follows.

1. A polyisocyanate composition derived from an aliphatic diisocyanate monomer and an alcohol and satisfying all of the following conditions in a solvent-free state.
1) Isocyanurate trimer concentration: 55 to 95% by mass.
2) Molar ratio of allophanate group / isocyanurate group: 5 to 50%
3) Mole ratio of uretdione group / isocyanurate group: 15-50%.
4) Molar ratio of [(allophanate group + uretdione group) / (isocyanurate group)]: 20 to 100%.
5) Isocyanate group average number: 2.5-3.5
6) Diisocyanate monomer concentration: 1% by mass or less.
7) Viscosity at 25 ° C .; 150 to 700 mPa · s.
8) Isocyanate group concentration: 22.0-25.0 mass%.
2. The polyisocyanate composition according to (1), wherein the alcohol is a monoalcohol.
3. The polyisocyanate composition according to (1) or (2), wherein the isocyanurate trimer concentration is 60 to 95% by mass.
4). The polyisocyanate composition according to any one of (1) to (3), wherein the aliphatic diisocyanate is hexamethylene diisocyanate.
5. The coating composition containing the polyisocyanate composition as described in any one of (1)-(4).

  The polyisocyanate composition of the present invention maintains high crosslinkability, has a low viscosity, generates little diisocyanate monomer during storage of the polyisocyanate, and has a high coating film hardness and excellent coating when used as a curing agent. A polyisocyanate composition capable of exhibiting film smoothness and a coating composition using the same as a curing agent can be provided.

The present invention is described in detail below.
The aliphatic diisocyanate monomer (hereinafter also simply referred to as diisocyanate) that can be used in the polyisocyanate composition of the present invention is a diisocyanate compound that does not contain a benzene ring in its structure. As the aliphatic diisocyanate monomer, those having 4 to 30 carbon atoms are preferable, and examples thereof include tetramethylene-1,4-diisocyanate, pentamethylene-1,5-diisocyanate, and hexamethylene diisocyanate. Of these, hexamethylene diisocyanate (HDI) is preferred from the viewpoint of weather resistance and industrial availability. Aliphatic diisocyanates may be used alone or in combination.

The alcohol that can be used in the polyisocyanate composition of the present invention is preferably an alcohol formed only of carbon, hydrogen, and oxygen, and more preferably a monoalcohol. A molecular weight of 200 or less is particularly preferable. Specific examples of the compound include methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol and other monoalcohols, ethylene glycol, 1,3-butanediol, neopentyl glycol, 2-ethyl. There are dialcohols such as hexanediol, and two or more kinds can be used in combination.

  The isocyanurate trimer, which is one of the components of the polyisocyanate composition of the present invention, is a polyisocyanate having an isocyanurate group consisting of three molecules of a diisocyanate monomer, and is represented by the following formula.

The concentration of the isocyanurate trimer is 55 to 95% by mass, and the lower limit is preferably 58%, more preferably 62%. As an upper limit, Preferably it is 90%, More preferably, it is 85%, More preferably, it is 80%. When the amount is less than 55% by mass, the viscosity of the polyisocyanate composition increases and the crosslinkability decreases, and when it exceeds 95% by mass, the viscosity increases.
The allophanate group, which is one of the components of the polyisocyanate composition of the present invention, is formed from a hydroxyl group of an alcohol and an isocyanate group, and is represented by the following formula.

  The molar ratio of allophanate groups / isocyanurate groups derived from alcohol is 5-50%. The lower limit is preferably 8%, more preferably 12%, still more preferably 16%, and most preferably 20%. The upper limit is preferably 45%, more preferably 40%, still more preferably 35%, and most preferably 30%. When the molar ratio is less than 5%, the viscosity of the resulting polyisocyanate composition may increase. When it exceeds 50%, the coating film hardness may decrease when used as a curing agent.

  The uretdione dimer, which is one of the constituent components of the polyisocyanate composition of the present invention, is a compound having a uretdione group composed of two molecules of a diisocyanate monomer, and is represented by the following formula.

The molar ratio of uretdione group / isocyanurate group is 15-50%. The lower limit is preferably 20%, more preferably 25%, and even more preferably 30%. The upper limit is preferably 45%, and more preferably 40%.
When the molar ratio is less than 15%, the viscosity of the polyisocyanate composition may increase, and when it exceeds 50%, the crosslinkability may decrease.

  The molar ratio of [(allophanate group + uretdione group) / (isocyanurate group)] is 20 to 100%. The lower limit is preferably 25%, more preferably 30%, still more preferably 35% or more, and most preferably 40% or more. The upper limit is preferably 90%, more preferably 80%, and even more preferably 70%.

  When the molar ratio is less than 20%, the viscosity of the polyisocyanate composition may increase. When it exceeds 100%, the coating film hardness decreases or the crosslinkability decreases when used as a curing agent. There is a case.

  The average number of isocyanate groups in the polyisocyanate composition of the present invention (which is a statistical average number of isocyanate groups contained in one molecule of polyisocyanate, calculated by the following formula) is 2.5 to 3.5. The lower limit is preferably 2.6, and more preferably 2.7. As an upper limit, Preferably it is 3.4, More preferably, it is 3.3, More preferably, it is 3.2.

When the lower limit is less than 2.5, the crosslinkability is lowered, and when the upper limit is 3.5, the viscosity of the polyisocyanate composition may increase. The average number of isocyanate groups is determined by the following formula.
Isocyanate group average number = [(polyisocyanate number average molecular weight × isocyanate group concentration) / (42 × 100)] (unit of isocyanate group concentration is mass%)

  The diisocyanate monomer concentration of the polyisocyanate composition of the present invention is 1.0% by mass or less. Preferably it is 0.5 mass% or less, More preferably, it is 0.3 mass% or less. If it exceeds 1.0% by mass, the crosslinkability is lowered, which is not preferable.

  The viscosity at 25 ° C. of the polyisocyanate composition of the present invention is 150 to 700 mPa · s. The upper limit is preferably 650 mPa · s, more preferably 600 mPa · s, still more preferably 550 mPa · s, and most preferably 500 mPa · s. If it is less than 150 mPa · s, the crosslinkability is lowered, and if it exceeds 700 mPa · s, the solid content concentration of the used paint is lowered, which is not preferable.

The isocyanate group concentration of the polyisocyanate composition of the present invention is preferably 22 to 25% by mass. If it is less than 22% by mass, the physical properties of the coating film such as the coating film hardness are lowered, and if it exceeds 25% by mass, the concentration of the diisocyanate monomer increases, which is not preferable.
The measuring method of an isocyanate group density | concentration is implemented according to the method as described in JISK7301-1995 (Tolylene diisocyanate type prepolymer test method for thermosetting urethane elastomers).

Hereinafter, the present invention will be described with reference to specific production methods.
The polyisocyanate composition of the present invention comprises an isocyanurate reaction for forming an isocyanurate group derived from an isocyanate group, an uretdione reaction for forming a uretdione group, and an allophanate reaction derived from an isocyanate group and a hydroxyl group of an alcohol. The reaction can be carried out in the presence of an excess of diisocyanate monomer, and after completion of the reaction, it can be obtained by removing unreacted diisocyanate monomer.

  Examples of the catalyst for deriving the isocyanurate group-containing polyisocyanate from the diisocyanate monomer include generally used isocyanurate-forming catalysts.

  As the isocyanuration catalyst, for example, a catalyst having basicity is generally preferred. (1) Tetraalkylammonium hydroxide such as tetramethylammonium and tetraethylammonium, and organic weak acid salts such as acetic acid and capric acid, (2) For example, hydroxyalkylammonium hydroxides such as trimethylhydroxypropylammonium, trimethylhydroxyethylammonium, triethylhydroxypropylammonium, triethylhydroxyethylammonium, etc., organic weak acid salts such as acetic acid and capric acid, (3) acetic acid, caproic acid, octylic acid , Alkali metal salts such as tin, zinc and lead of alkyl carboxylic acids such as myristic acid, (4) metal alcoholates such as sodium and potassium, (5) examples If aminosilyl group-containing compound such as hexamethyldisilazane, (6) Mannich bases, (7) in combination with tertiary amines with epoxy compounds, (8) for example, phosphorus compounds such as tributylphosphine and the like.

  Of these, quaternary ammonium organic weak acid salts are preferred, and tetraalkylammonium organic weak acid salts are more preferred. The aminosilyl group-containing compound is not preferable because it results in the formation of a polyisocyanate having a biuret group and a monoisocyanate having a urethane bond.

  These catalysts are preferably 10 to 1000 ppm based on the charged diisocyanate mass. As an upper limit, it is more preferable that it is 500 ppm, More preferably, it is 100 ppm.

  As isocyanuration reaction temperature, 50-120 degreeC is preferable, More preferably, it is 60-90 degreeC. If the isocyanurate reaction temperature exceeds 120 ° C., coloring or the like occurs, which is not preferable.

  The isocyanuration reaction is stopped by adding an acidic compound such as phosphoric acid and acidic phosphate ester at a desired conversion rate (mass ratio of the polyisocyanate produced by the isocyanuration reaction to the charged diisocyanate monomer). In order to obtain the polyisocyanate of the present invention, it is necessary to stop the progress of the reaction at the initial stage. However, the cyclic trimerization of the isocyanate group has a very high initial reaction rate, so it is difficult to stop the progress of the reaction at the initial stage, and the reaction conditions, particularly the addition amount and addition method of the catalyst, are carefully considered. Must be selected. For example, it is recommended that a catalyst addition method at regular intervals is suitable. Accordingly, the conversion of the isocyanurate conversion reaction for obtaining the isocyanurate trimer concentration range of the present invention is preferably 30% or less, more preferably 25% or less, and still more preferably 20% or less. If it exceeds 30%, it may be difficult to achieve the isocyanurate trimer concentration, which is a constituent of the present invention, and the resulting polyisocyanate composition may not be compatible with high solidity and crosslinkability.

  The obtained isocyanurate group-containing polyisocyanate may contain pentamer, heptamer and the like in addition to the isocyanurate trimer. At the same time, a polyisocyanate other than an isocyanurate group-containing polyisocyanate such as a uretdione group-containing polyisocyanate may be formed at the same time. The uretdione dimer concentration produced at the time of the isocyanuration reaction is 2% by mass or less, preferably 1% by mass or less, based on the polyisocyanate produced by the isocyanuration reaction. That is, at this stage, it is necessary to select a catalyst with less uretdione formation. In particular, it was surprising that the diisocyanate monomer generated during storage of the resulting polyisocyanate composition can be further suppressed by carrying out the isocyanuration reaction in the formation or presence of allophanate bonds described below.

The formation of allophanate bonds in the polyisocyanate composition of the present invention will be described.
The amount of alcohol added is 1000/1 to 10/1, preferably 1000/1 to 100/1, in terms of the equivalent ratio of the isocyanate group of the diisocyanate monomer to the hydroxyl group of the alcohol. If it is less than 10/1, the average number of isocyanate groups decreases, which is not preferable. In order to produce an allophanate group, an allophanate reaction catalyst is usually used. Examples of the specific compound include alkyltin salts such as tin, lead, zinc, bismuth, zirconium and zirconyl, and organic tin compounds such as tin 2-ethylhexanoate and dibutyltin dilaurate, and 2-ethylhexane. Organic lead compounds such as lead acid, organic zinc compounds such as zinc 2-ethylhexanoate, bismuth 2-ethylhexanoate, zirconium 2-ethylhexanoate, zirconyl 2-ethylhexanoate, etc. be able to.

  In addition, the above isocyanurate reaction catalyst can also be an allophanate reaction catalyst. When performing the allophanatization reaction using the above isocyanurate reaction catalyst, the isocyanurate group-containing polyisocyanate is naturally produced. In view of economic production, it is preferable to perform the allophanate reaction and the isocyanurate reaction by using the above isocyanurate reaction catalyst as the allophanate reaction catalyst.

  The uretdione dimer is obtained using a uretdione formation reaction catalyst. Examples of this specific compound are tertiary phosphines such as trialkylphosphine such as tri-n-butylphosphine and tri-n-octylphosphine, and tris (dialkylamino) phosphine such as tris- (dimethylamino) phosphine. And 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 obtained, a quenching agent for a uretdione reaction catalyst such as phosphoric acid or methyl paratoluenesulfonate is added to stop the uretdione reaction.

  Moreover, a uretdione dimer can also be obtained by heating the monomer of a diisocyanate, without using the above catalysts. The heating temperature is 120 ° C. or higher, preferably 130 to 170 ° C., more preferably 140 to 160 ° C., and the heating time is 0.5 Hr to 4 Hr, preferably 1 to 3 Hr, more preferably. 1-2Hr.

  In order to obtain the polyisocyanate composition of the present invention, preferably, the uretdioneation reaction catalyst is not used, and after completion of the uretdioneation reaction by heating alone, the above-mentioned isocyanurate reaction and allophanate reaction, unreacted diisocyanate monomer is added. Remove. It was surprising that the unreacted diisocyanate monomer concentration in the resulting polyisocyanate composition was low and the increase in unreacted diisocyanate monomer concentration was suppressed after storage.

  The above-described isocyanuration reaction, allophanation reaction, and uretdiionization reaction can be performed sequentially or some of them can be performed in parallel. Preferably, the isocyanuration reaction and the allophanatization reaction are preceded in parallel, and then the uretdioneization reaction is performed. More preferably, the isocyanurate formation reaction and the allophanatization reaction are simultaneously performed using a common catalyst, and then the uretdione conversion reaction by heat is performed, so that the production process can be simplified.

  The unreacted disoisocyanate monomer is removed from the reaction solution after completion of the reaction by thin-film distillation, extraction or the like, and the polyisocyanate composition of the present invention can be obtained.

  The average number of isocyanate groups is 2, allophanate group-containing polyisocyanates derived from uretdione dimer and monoalcohol are each at a specific concentration, and the molar ratio of the total amount of uretdione groups and allophanate groups to isocyanurate groups is The polyisocyanate composition of the present invention, which is in a specific range, has a low cross-linking property, high crosslinkability, high coating film hardness after drying, good weather resistance, and smooth coating after drying. It was surprising that the properties were excellent.

  The polyisocyanate composition of the present invention preferably contains no biuret type polyisocyanate. The presence of biuret-type polyisocyanates leads to an increase in diisocyanate monomers after storage of the polyisocyanate composition, which is not preferred. Preferably, its presence is 1.0% by weight or less, more preferably 0.5% by weight or less.

  The increase in the diisocyanate monomer concentration when the obtained polyisocyanate composition of the present invention is stored at 40 ° C. for one month is 0.6% by mass or less, preferably 0.5% by mass or less, more preferably 0.4% by mass or less.

  Moreover, blocked polyisocyanate can be obtained by blocking the isocyanate group of the obtained polyisocyanate composition with a blocking agent. The following can be mentioned as a blocking agent which can be used here.

  The blocking agent that can be used in the present invention is a compound having one active hydrogen in the molecule, for example, alcohol, alkylphenol, phenol, active methylene, mercaptan, acid amide, and acid imide. Imidazole, urea, oxime, amine, imide, and pyrazole compounds. Examples of more specific blocking agents are shown below.

(1) Alcohols such as methanol, ethanol, 2-propanol, n-butanol, sec-butanol, 2-ethyl-1-hexanol, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, etc. (2) alkylphenols Mono- and dialkylphenols having an alkyl group having 4 or more carbon atoms as a substituent, such as n-propylphenol, isopropylphenol, n-butylphenol, sec-butylphenol, t-butylphenol, n-hexylphenol, 2; -Monoalkylphenols such as ethylhexylphenol, n-octylphenol, n-nonylphenol, di-n-propylphenol, diisopropylphenol, isopropylcresol, di-n-butylphenol Dialkylphenols such as phenol, cresol, ethylphenol, di-tert-butylphenol, di-sec-butylphenol, di-n-octylphenol, di-2-ethylhexylphenol, di-n-nonylphenol (4) Active methylene series; dimethyl malonate, diethyl malonate, methyl acetoacetate, ethyl acetoacetate, acetylacetone, etc. (5) mercaptan series; butyl mercaptan, dodecyl mercaptan, etc. (6) Acid amides; acetanilide, acetic acid amide, ε-caprolactam, δ-valerolactam, γ-butyrolactam, etc. (7) acid imides; succinimide, maleic imides, etc. (8) imidazole; imidazole, 2-methyl (9) Urea type; urea, thiourea, ethylene urea, etc. (10) oxime type; formald oxime, acetald oxime, acetoxime, methyl ethyl ketoxime, cyclohexanone oxime, etc. (11) amine type; diphenylamine, aniline, carbazole , N-propylamine, diisopropylamine, isopropylethylamine and the like (12) imine type; ethyleneimine, polyethyleneimine and the like (13) pyrazole type; pyrazole, 3-methylpyrazole, 3,5-dimethylpyrazole and the like.

A preferred blocking agent is at least one selected from alcohols, oximes, acid amides, active methylenes, and pyrazoles.
The coating composition of the present invention can be obtained by mixing the polyisocyanate composition of the present invention with a polyol as a curing agent.

  Examples of this polyol include polyester polyol, acrylic polyol, polyether polyol, polyolefin polyol, fluorine polyol, polycarbonate polyol, and epoxy polyol.

  As the polyester polyol, for example, a dibasic acid selected from the group of carboxylic acids such as succinic acid, adipic acid, sebacic acid, dimer acid, maleic anhydride, phthalic anhydride, isophthalic acid, terephthalic acid, or a mixture thereof, Polyester polyol obtained by a condensation reaction with a single or mixture of polyhydric alcohols selected from the group such as ethylene glycol, propylene glycol, diethylene glycol, neopentyl glycol, trimethylolpropane, glycerin and the like, and ε- using polyhydric alcohol, for example And polycaprolactones obtained by ring-opening polymerization of caprolactone.

  Acrylic polyol is obtained by copolymerizing an ethylenically unsaturated bond-containing monomer having a hydroxyl group alone or a mixture thereof with another ethylenically unsaturated bond-containing monomer alone or a mixture thereof. can get.

  Examples of the ethylenically unsaturated bond-containing monomer having a hydroxyl group include hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, and hydroxybutyl methacrylate. It is done. Preferred are hydroxyethyl acrylate and hydroxyethyl methacrylate.

  Other ethylenically unsaturated bond-containing monomers copolymerizable with the above monomers include methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, Acrylic acid esters such as acrylic acid-n-hexyl, cyclohexyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, benzyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate Methacrylic acid-n-butyl, isobutyl methacrylate, methacrylic acid-n-hexyl, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, benzyl methacrylate, phenyl methacrylate, etc. Acid esters, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, acrylamide, methacrylamide, N, N-methylenebisacrylamide, diacetone acrylamide, diacetone methacrylamide, maleic acid amide, maleimide, etc. Unsaturated amides and vinyl monomers such as glycidyl methacrylate, styrene, vinyl toluene, vinyl acetate, acrylonitrile, dibutyl fumarate, vinyltrimethoxysilane, vinylmethyldimethoxysilane, γ- (meth) acryloxypropyltrimethoxy Examples thereof include vinyl monomers having hydrolyzable silyl groups such as silane.

  Polyether polyols include, for example, ethylene oxide, propylene oxide, a single or mixture of polyvalent hydroxy compounds, using, for example, hydroxides such as lithium, sodium and potassium, strong basic catalysts such as alcoholates and alkylamines. Polyether polyols obtained by adding a single or mixture of alkylene oxides such as butylene oxide, cyclohexene oxide and styrene oxide, polyether polyols obtained by reacting alkylene oxide with a polyfunctional compound such as ethylenediamine, and So-called polymer polyols obtained by polymerizing acrylamide or the like using these polyethers as a medium are included.

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

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

  The number of hydroxyl groups (hereinafter, the average number of hydroxyl groups) possessed by one statistical molecule of polyol is preferably 2 or more. When the average number of hydroxyl groups is less than 2, the resulting coating film may have a reduced crosslinking density.

  The fluorine polyol is a polyol containing fluorine in the molecule. For example, fluoroolefin, cyclovinyl ether, hydroxyalkyl vinyl ether, vinyl monocarboxylate disclosed in JP-A-57-34107 and JP-A-61-275111. There are copolymers such as esters.

  Polycarbonate polyols include polyalkylenes such as dialkyl carbonates such as dimethyl carbonate, alkylene carbonates such as ethylene carbonate, low molecular carbonate compounds such as diaryl carbonates such as diphenyl carbonate, and low molecular polyols used in the aforementioned polyester polyols. What is obtained is mentioned.

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

  It is preferable that the resin solid content concentration of the polyol used is 60 to 100% by mass. As a lower limit, More preferably, it is 70 mass%, More preferably, it is 75 mass%. If it is less than 60% by mass, it is difficult to reduce VOC. Moreover, it is preferable that molecular weight is 500-10000. The lower limit is preferably 700, more preferably 1000. As an upper limit, Preferably, it is 7000, More preferably, it is 5000. When the molecular weight exceeds 10,000, the viscosity of the polyol increases, making it difficult to achieve a high resin concentration. When the molecular weight is less than 500, the mechanical properties of the cured coating film may be lowered. The resin hydroxyl value of the polyol is 10 to 300 mg KOH / resin g, preferably 30 to 200 mg KOH / resin g. When the hydroxyl value is less than 10 mgKOH / resin g, the crosslinking density decreases, and the physical properties intended by the present invention cannot always be achieved sufficiently. When the hydroxyl value exceeds 300 mgKOH / resin g, In some cases, the crosslink density increases and the mechanical properties of the coating film decrease.

  If necessary, it can have an acid value of 30-50 mg KOH / g resin. The glass transition point is −20 to 100 ° C., and in the case of acrylic polyol, it can be calculated from the Fox equation.

  In the coating composition of the present invention, the equivalent ratio of the isocyanate group of the polyisocyanate composition to the hydroxyl group of the polyol is preferably 5/1 to 1/5, more preferably 5/3 to 3/5, still more preferably 5 /. 4 to 4/5.

  Further, in order to adjust the high solid paint, the use of a volatile component is not preferable, and it should be kept in a small amount even when used, but various solvents and additives can be used depending on the purpose and purpose. 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, alcohols such as butanol and isopropyl alcohol, toluene, xylene, cyclohexane, and mineral spirits. From the group consisting of hydrocarbons such as naphtha, etc., they can be appropriately selected according to the purpose and use. These solvents may be used alone or in combination of two or more.

  Further, if necessary, curing accelerators, for example, organic metal compounds such as carboxylic acids such as tin, zinc, lead, antioxidants, for example, hindered phenol, ultraviolet absorbers, for example, benzotriazole, benzophenone, etc. Pigments such as titanium oxide, carbon black, indigo, quinacridone and pearl mica, metal powder pigments such as aluminum, and rheology control agents such as hydroxyethyl cellulose and urea compounds may be added.

  The resin solid content concentration which is the total mass ratio of the polyol and the polyisocyanate composition in the coating composition of the present invention is preferably 50% by mass or more, more preferably 53% by mass, and still more preferably 56% by mass or more. Most preferably, it is 60 mass% or more.

  It was surprising that the coating composition thus prepared enhanced the physical properties of the undercoat. This is particularly noticeable when the base coating film is uncured. When the coating composition of the present invention is applied on an uncured coating film and cured, the adhesion between the base coating film and the substrate is remarkably improved.

  The coating composition thus prepared can also be used for adhesives, inks, casting agents and the like. Examples of the coating method include roll coating, curtain flow coating, spray coating, cation and anion electrodeposition coating. Examples of the material of the object to be coated include inorganic materials such as metal, plastic, cement, calcium silicate, and gypsum. When the coating composition of the present invention is used as a primer or top intermediate coating on these materials, it can be applied to pre-coated metals, automobile coatings, etc. that contain rust-proof steel sheets, cosmetics, weather resistance, acid resistance, rust resistance, chipping resistance, etc. Can be useful.

  In particular, in the coating composition of the present invention, the coating film to be formed has a urethane bond and is tough, the coating film hardness is high, the surface smoothness and the chemical resistance are good, and further the adhesion to the organic coating film Because of its excellent properties, it is useful as a non-aqueous base coat containing a pigment and a top clear coat to be coated on an aqueous base coat. The base coat and the top clear coat are preferably cured simultaneously.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to the following examples.

(Viscosity measurement)
Using an E type viscometer (VISCONIC ED type (trade name) manufactured by Tokimec Co., Ltd.), the measurement was performed at 25 ° C.

(Measurement of number average molecular weight)
The number average molecular weight of the polyisocyanate composition is a polystyrene-based number average molecular weight measured by gel permeation chromatography (hereinafter referred to as GPC) using the following apparatus.
Equipment: Tosoh Corporation HLC-8120GPC (trade name)
Column: Tosoh Corporation TSKgel SuperH1000 (trade name) x 1
TSKgel SuperH2000 (trade name) x 1
TSKgel SuperH3000 (trade name) x 1 Carrier: Tetrahydrofuran Detection method: Differential refractometer

(Measurement of isocyanate group mass concentration)
The measuring method of an isocyanate group density | concentration is implemented according to the method as described in JISK7301-1995 (Tolylene diisocyanate type prepolymer test method for thermosetting urethane elastomers).

A specific method is shown below.
1) Take 1 g of a sample in a 200 ml Erlenmeyer flask and add 20 ml of toluene to dissolve.
2) Then, 20 ml of 2.0N di-n-butylamine / toluene solution is added and allowed to stand for 15 minutes.
3) Add 70 ml of 2-propanol.
4) Titrate with 1.0N hydrochloric acid and measure the isocyanate group mass concentration.
5) Even when no sample is added, the measurement is performed in the same manner as described above.

(Average number of isocyanate groups)
The average number of isocyanate groups was calculated from the following formula using the measurement results of the number average molecular weight of the polyisocyanate and the isocyanate group concentration.
Isocyanate group average number = [(polyisocyanate number average molecular weight × isocyanate group concentration) / (42 × 100)]

(Measurement of isocyanurate trimer concentration)
Gel permeation chromatograph measurement was performed in the same manner as the number average molecular weight measurement, and the peak area% corresponding to the molecular weight three times that of diisocyanate was shown as the isocyanurate trimer concentration.

(Molar ratio of allophanate group / isocyanurate group)
The molar ratio of allophanate groups and isocyanurate groups was determined by ¹ H-NMR measurement using FT-NMR DPX-400 (trade name) manufactured by Bruker.
The allophanate group used the hydrogen signal on the nitrogen atom of the allophanate group near 8.5 ppm, and the isocyanurate group used the hydrogen signal of the methylene group next to the nitrogen atom of the isocyanurate ring near 3.8 ppm. It calculated | required from each area ratio.

(Measurement of uretdione dimer concentration)
Gel permeation chromatographic measurement similar to the number average molecular weight measurement was performed, and the peak area% corresponding to the molecular weight twice that of diisocyanate was shown as the uretdione dimer concentration. Moreover, the mass% (Ut-1) of the uretdione dimer in the polyisocyanate (not including the unreacted diisocyanate) produced by the isocyanuration reaction, and the mass% (Ut of the uretdione dimer after removal of the unreacted diisocyanate monomer). -2) was measured respectively.

(Mole ratio of uretdione group / isocyanurate group)
The molar ratio of the uretdione group and the isocyanurate group was determined by measurement of ¹³ C-NMR using Biospin Avance 600 (trade name) manufactured by Bruker.
The uretdione group uses the carbon atom signal of the 4-membered ring carbonyl group near 157.3 ppm, and the isocyanurate group uses the carbon element signal of the 6-membered ring carbonyl group near 148.6 ppm. It was calculated from the ratio.

(Mole ratio of biuret group / isocyanurate group)
The molar ratio of allophanate groups and isocyanurate groups was determined by ¹ H-NMR measurement using FT-NMR DPX-400 (trade name) manufactured by Bruker.
The biuret group used the hydrogen signal on the nitrogen atom of the biuret group near 7.1 ppm, and the isocyanurate group used the hydrogen signal of the methylene group next to the nitrogen atom of the isocyanurate ring near 3.8 ppm. It calculated | required from each area ratio.

(Mole ratio of [(total of allophanate group and uretdione group) / isocyanurate group])
[Mole ratio of (total of allophanate group and uretdione group) / (isocyanurate group)] was determined by measurement of ¹³ C-NMR using Biospin Avance 600 (trade name) manufactured by Bruker.
The allophanate group uses the signal of the carbon atom of the carbonyl group derived from the allophanate group near 154.0 ppm, and the uretdione group uses the signal of the carbon atom of the 4-membered ring carbonyl group around 157.3 ppm, and isocyanurate group Was determined from the respective area ratios using the carbon element signal of the 6-membered carbonyl group in the vicinity of 148.6 ppm.

(Measurement of isocyanurate conversion rate)
The reaction liquid refractive index was determined by measurement.

(Mass concentration of diisocyanate monomer before and after storage of polyisocyanate composition)
After the polyisocyanate composition was stored at 40 ° C. for 1 month in a nitrogen atmosphere, the diisocyanate monomer concentration was measured by gas chromatograph measurement under the following conditions. The case where the increase in the concentration of the diisocyanate monomer after storage is 0.2% by mass or less, ◯ is 0.3% by mass or less, Δ is 0.4% or less, and x is 0.5% by mass.
Gas chromatograph measurement conditions ・ Column Silicon OV17 1m
・ Inlet temperature 160 ℃, Column temperature 120 ℃
・ Carrier Nitrogen ・ Detector Hydrogen flame ionization detector

(High solidity)
Acrylic polyol (Nuplex brand name Setalux 1903, resin solid content concentration 75%, hydroxyl value 150 mg KOH / resin g) and polyisocyanate composition were mixed so that the equivalent ratio of hydroxyl group to isocyanate group was 1.0, and further thinner As a Ford Cup No. 2 mixture of ethyl acetate / toluene / butyl acetate / xylene / propylene glycol monomethyl ether acetate (mass ratio 30/30/20/15/5). It was diluted so that the viscosity measured in 4 was 20 seconds. In the above composition, the case where the solid content of the paint was 56% or more was indicated as ◎, the case where it was 55% or more and less than 56% was indicated as ◯, and the case where it was less than 55% was indicated as ×.

(Gel fraction)
Before the immersion of the undissolved partial mass when the applicator is coated on a polypropylene plate so that the resin film thickness is 50 μm, and the cured coating film is left to stand for 24 hours at 20 ° C. and humidity of 65 Rh% is immersed in acetone at 20 ° C. for 24 hours. The value with respect to the mass was calculated. Less than 80% was represented by x, 80% or more and less than 85% was represented by Δ, 85% or more and less than 90% was represented by ○, and 90% or more was represented by ◎.

(Coating hardness)
The König hardness of a 50 μm-thickness coating film coated on a glass plate and cured at 90 ° C. for 30 minutes was measured at 20 ° C. with a pendulum type hardness meter of BYK Chemie. When the coating film hardness was less than 44, x was expressed as x, 45-49 as Δ, 50-54 or more as ◯, and 55 or more as ◎.

(Undercoat film adhesion)
Acrylic polyol (resin solid content concentration 55%, hydroxyl value 30 mgKOH / resin g) was applied to a mild steel plate so that the resin film thickness was 40 micrometers, and allowed to stand at room temperature for 30 minutes, then acrylic polyol (Nuplex product name, Setalux 1903). The resin solid content concentration is 75%, the hydroxyl value is 150 mg KOH / resin g) and the polyisocyanate composition is blended so that the equivalent ratio of hydroxyl group to isocyanate group is 1: 1.3, and then thinner (ethyl acetate / toluene / butyl acetate / Xylene / propylene glycol monomethyl ether acetate = 30/30/20/15/5 (mass ratio)) The coating composition adjusted so as to be 20 seconds at 4 was applied so as to have a resin film thickness of 30 micrometers. After standing at room temperature for 15 minutes, it was cured in an oven at 90 ° C. for 30 minutes. The adhesion test of this coating film was performed according to JIS K5600-5-6. The case where there was no release coating film was shown as ○, and the case where there was a release coating film was shown as x.

(Coating surface smoothness)
The smoothness of the coating film surface with a film thickness of 30 μm coated on mild steel plate and cured at 60 ° C. for 30 minutes using Zygo's non-contact surface shape measuring instrument NewView 600s, is observed with a scanning white interference method 2.8. The measurement was performed under the conditions of × 2.1 mm and objective lens 2.5 times. The case where the unevenness | corrugation of the perpendicular direction was less than 0.025 micrometer was shown as (circle) and the case where 0.025 micrometer or more was shown as x.

(Example 1) (Production of polyisocyanate composition)
A four-necked flask equipped with a stirrer, thermometer, reflux condenser, nitrogen blowing tube, and dropping funnel was placed in a nitrogen atmosphere, and 600 parts of HDI and 2.5 parts of isobutanol were charged. The temperature was maintained at 2 ° C. for 2 hours. Thereafter, 0.5 part of a solution obtained by diluting the isocyanurate-forming catalyst trimethyl-2-methyl-2-hydroxyethylammonium hydroxide with isobutanol to 5% by mass was added to carry out an isocyanuration reaction. When the concentration reached%, phosphoric acid was added to stop the reaction. The uretdione dimer mass concentration increased by this reaction was 1% or less. 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 properties of the resulting polyisocyanate composition are shown in Table 1.

(Example 2)
The same procedure as in Example 1 was performed except that 1.1 parts of isobutanol was added. The results are shown in Table 1.

(Example 3)
The same procedure as in Example 1 was conducted except that 3.7 parts of isobutanol was added. The results are shown in Table 1.

Example 4
It implemented like Example 1 except having changed the heating conditions after adding phosphoric acid and stopping reaction to 160 degreeC and 0.5 Hr. The results are shown in Table 1.

(Example 5)
The same procedure as in Example 1 was performed except that 0.7 part of isobutanol was added and the conversion rate was 20%. The results are shown in Table 1.
Show.

(Comparative Example 1)
The same procedure as in Example 1 was conducted, except that 6.5 parts of isobutanol was added and the conversion rate was 20%. The results are shown in Table 1.

(Comparative Example 2)
The inside of the apparatus similar to Example 1 was made into nitrogen atmosphere, 600 parts of HDI were prepared, and the reactor internal temperature was hold | maintained at 160 degreeC and 1.5 Hr with stirring. Thereafter, the temperature in the reactor was lowered to 140 ° C., 6 parts of isocyanuration reaction catalyst hexamethyldisilazane was added, and the mixture was held for 30 minutes. Further, the temperature in the reactor was lowered to 90 ° C., 3.3 parts of n-butanol was added, and maintained for 1 hour. After cooling the reaction solution, unreacted HDI was removed using a thin film evaporator. The properties of the resulting polyisocyanate composition are shown in Table 1.

(Comparative Example 3)
The inside of the apparatus similar to Example 1 was made into nitrogen atmosphere, 600 parts of HDI was prepared, and the temperature in a reactor was kept at 60 degreeC under stirring. 9 parts of tri-n-butylphosphine (Cytop (trademark) 340, Cytec), which is a uretdione reaction catalyst, was added thereto, and uretdione reaction and isocyanurate reaction were carried out. When the conversion rate reached 40%. The reaction was stopped by adding 12 parts of methyl-p-toluenesulfonate. The reaction solution was cooled, filtered, and unreacted HDI was removed using a thin film evaporator. The properties of the resulting polyisocyanate composition are shown in Table 1.

(Comparative Example 4)
The inside of the apparatus similar to Example 1 was made into nitrogen atmosphere, 600 parts of HDI was prepared, and the temperature in a reactor was kept at 60 degreeC under stirring. 1.0 part of a solution obtained by diluting trimethyl-2-methyl-2-hydroxyethylammonium hydroxide, which is an isocyanuration reaction catalyst, to 5% by mass with isobutanol was added to the allophanation reaction and isocyanuration. Reaction was performed, and when the conversion rate reached 22%, phosphoric acid was added to stop the reaction. The reaction solution was cooled, filtered, and unreacted HDI was removed using a thin film evaporator. The properties of the resulting polyisocyanate composition are shown in Table 1.

(Comparative Example 5)
The same procedure as in Example 2 was performed except that the heating condition after adding phosphoric acid and stopping the reaction was changed to 130 ° C. and 1 Hr. The results are shown in Table 1.

(Comparative Example 6)
The same procedure as in Example 2 was repeated except that 0 part of isobutanol was added and the conversion rate was 21%. The results are shown in Table 1.

(Example 6-10, Comparative Example 7-12)
After blending an acrylic polyol (Nuplex product name, Setalux 1903, resin solids concentration 75%, hydroxyl value 150 mg KOH / resin g) and a polyisocyanate composition so that the hydroxyl group and isocyanate group equivalent ratio is 1.0, thinner (acetic acid Ethyl / toluene / butyl acetate / xylene / propylene glycol monomethyl ether acetate = 30/30/20/15/5 (mass ratio)) 4 was adjusted to 20 seconds, and the coating film hardness and coating film gel fraction were evaluated. The results are shown in Table 2.

Claims (5)

A polyisocyanate composition derived from an aliphatic diisocyanate monomer and an alcohol and satisfying all of the following conditions in a solvent-free state.
1) Isocyanurate trimer concentration: 55 to 95% by mass.
2) Molar ratio of allophanate group / isocyanurate group: 5 to 50%
3) Mole ratio of uretdione group / isocyanurate group: 15-50%.
4) Molar ratio of [(allophanate group + uretdione group) / (isocyanurate group)]: 20 to 100%.
5) Isocyanate group average number: 2.5-3.5
6) Diisocyanate monomer concentration: 1% by mass or less.
7) Viscosity at 25 ° C .; 150 to 700 mPa · s.
8) Isocyanate group concentration: 22.0-25.0 mass%.   2. The polyisocyanate composition according to claim 1, wherein the alcohol is a monoalcohol.   The polyisocyanate composition according to claim 1 or 2, wherein the isocyanurate trimer concentration is 60 to 95% by mass.   The polyisocyanate composition according to any one of claims 1 to 3, wherein the aliphatic diisocyanate is hexamethylene diisocyanate.   The coating composition containing the polyisocyanate composition as described in any one of Claims 1-4.