JP6926489B2 - Method for producing modified organic polyisocyanate - Google Patents

Description

The present invention relates to a production method for stabilizing the color of a modified organic polyisocyanate.

Modified organic polyisocyanates modified from organic polyisocyanates are useful in the field of polyurethane plastics and are used in various fields. For example, it is used with polyols in the production of foams, fibers, films, elastomers and paints. In its use, the modified organic polyisocyanate is often diluted with an organic solvent before use. However, when the modified organic polyisocyanate is diluted with an organic solvent, it tends to discolor during storage. This property is especially noticeable when the modified organic polyisocyanate must be stored at a relatively high temperature.

It has already been proposed to add various stabilizers to the modified organic polyisocyanate in order to reduce the discoloration tendency of the modified organic polyisocyanate. Known stabilizers include sterically hindered phenol typified by 2,6-di-tert-butyl-4-methylphenol (hereinafter also referred to as BHT), dialkyldiphenylamine, phenothiazine, phosphite, and representatives of these compounds. There is a mixture of compounds (Patent Documents 1 and 2). However, it has not been clarified about reducing the discoloration tendency when the modified organic polyisocyanate is diluted with an organic solvent, and controlling the timing of adding a stabilizer in order to reduce the discoloration tendency.

The problems with BHT are that it is relatively volatile, tends to migrate into a support covered with polyurethane, and tends to turn yellow when diluted in an organic solvent and stored. That is. From these facts, there has been a demand for a stabilizer and a manufacturing method that overcomes the stability after dilution with an organic solvent and the problems of BHT.

U.S. Pat. No. 3715381 Japanese Unexamined Patent Publication No. 1994-92925

The present invention has been made in view of the above background techniques, and an object of the present invention is to provide a production method for improving color stability when a modified organic polyisocyanate is diluted and stored.

As a result of repeated studies, the present inventors have found that the above-mentioned problems can be solved by adding a specific compound at a specific timing in the production of a modified organic polyisocyanate, and have arrived at the present invention.

That is, the present invention includes the following embodiments [1] to [6].

[1] In the method for producing a modified organic polyisocyanate in which an organic diisocyanate monomer is isocyanurate or allophanate, a compound having a sterically impaired phenol structure after the formation of the modified organic polyisocyanate (however, 2,6-di-tert-). A method for producing a modified organic polyisocyanate, which comprises adding (excluding butyl-4-methylphenol).

[2] The compound having a sterically hindered phenol structure is tetrakis [methylene-3- (3', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane, 3- (3,5-di-). Octadecyl propanate (tert-butyl-4-hydroxyphenyl), octyl 3- (4-hydroxy-3,5-diisopropylphenyl) propionate, 1,3,5-tris (3,5-di-tert-butyl-4) -Hydroxybenzyl) Isocyanuric acid, 2,4,6-tris (3', 5'-di-tert-butyl-4'-hydroxybenzyl) is at least one selected from mecitylene, as described above [1]. ]. The method for producing a modified organic polyisocyanate.

[3] The method for producing a modified organic polyisocyanate according to the above [1] or [2], wherein the modified organic polyisocyanate is a modified product of hexamethylene diisocyanate.

[4] The modified organic polyisocyanate according to any one of the above [1] to [3], wherein the modified organic polyisocyanate contains at least one selected from the group consisting of an isocyanurate group and an allophanate group. Manufacturing method.

[5] A method for producing a two-component coating composition containing the modified organic polyisocyanate obtained by the production method according to any one of the above [1] to [4] and a polyol.

[6] A method for producing a coating film obtained from the two-component coating composition obtained by the above-mentioned production method [5].

The modified organic polyisocyanate produced by this production method can be advantageously used for the subsequent production of polyurethane because the tendency of discoloration during storage at high temperature is greatly reduced after dilution with an organic solvent.

Hereinafter, the present invention will be described in detail.

The modified organic polyisocyanate produced by this production method can be obtained by subjecting an organic diisocyanate monomer to an isocyanurate-forming or allophanate-forming reaction, and then adding a compound having a sterically hindered phenol structure other than BHT.

First, a specific method for producing the modified organic polyisocyanate of the present invention will be described.

In the first step, an organic diisocyanate monomer and a hydroxyl group-containing compound are charged in an amount in which an isocyanate group is excessive with respect to the hydroxyl group, and are urethanized and isocyanate at 50 to 150 ° C. in the presence or absence of an organic solvent. The isocyanate group-terminated prepolymer I is produced by carrying out at least one of the urethanization and allophanation reactions. As a guideline for the reaction here, the completion is judged by the isocyanate group content and the refractive index increase value by the neutralization titration method.

In the second step, the reaction is stopped by adding a reaction terminator to the isocyanate group-terminated prepolymer I.

In the third step, a compound having a sterically hindered phenol structure other than BHT is added to the isocyanate group-terminated prepolymer I.

In these first to third steps, the reaction is allowed to proceed under nitrogen gas or a dry air stream.

In the fourth step, the isocyanate group-terminated prepolymer I obtained in the third step is removed by thin film distillation or solvent extraction until the content of the free organic diisocyanate monomer is less than 1% by mass, and the modified organic polyisocyanate is removed. obtain.

Here, the "amount of excess isocyanate group" in the first step differs between the case of the isocyanurate-forming reaction and the case of the allophanate-forming reaction, and in the case of the isocyanurate-forming reaction, the molar ratio of the isocyanate group to the hydroxyl group. However, it is preferable to prepare so that R = isocyanate group / hydroxyl group becomes 100 to 2000, and it is more preferable to prepare so that R = 200 to 2000. In the case of the allophanation reaction, it is preferable to prepare so that the molar ratio of the isocyanate group to the hydroxyl group is 5 to 75 with R = isocyanate group / hydroxyl group, and it is more preferable to prepare so that R = 5 to 50. If it is less than the lower limit, the amount of the polyisocyanate composition having a higher molecular weight than the target product is increased, which may lead to an increase in viscosity. If it exceeds the upper limit, the viscosity may increase and the product yield may decrease, resulting in a decrease in productivity.

The organic diisocyanate monomer used in the first step is not particularly limited, and examples thereof include an aliphatic diisocyanate, an alicyclic diisocyanate, an aromatic diisocyanate, and an aromatic aliphatic diisocyanate.

<Alphatic diisocyanate>
Specific examples of the aliphatic diisocyanate include hexamethylene diisocyanate, tetramethylene diisocyanate, 2-methyl-pentane-1,5-diisocyanate, 3-methyl-pentane-1,5-diisocyanate, lysine diisocyanate, and trioxyethylene diisocyanate. These can be mentioned and mixtures of these can also be used.

<Alicyclic diisocyanate>
Specific examples of the alicyclic diisocyanate include isophorone diisocyanate, cyclohexane diisocyanate, hydrogenated diphenylmethane diisocyanate, norbornan diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylene diisocyanate, hydrogenated tetramethylxylene diisocyanate, and the like. Mixtures can also be used.

<Aromatic diisocyanate>
Specific examples of aromatic diisocyanates include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, and 2,2'-diphenylmethane diisocyanate, 4 , 4'-diphenyl ether diisocyanate, 2-nitrodiphenyl-4,4'-diisocyanate, 2,2'-diphenylpropane-4,4'-diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, 4 , 4'-diphenylpropane diisocyanate, m-phenylenediocyanate, p-phenylenediocyanate, naphthylene-1,4-diisocyanate, naphthylene-1,5-diisocyanate, 3,3'-dimethoxydiphenyl-4,4'-diisocyanate, etc. These can be mentioned and mixtures of these can also be used.

<Aromatic aliphatic diisocyanate>
Specific examples of the aromatic aliphatic diisocyanate include 1,3- or 1,4-xylylene diisocyanate, 1,3- or 1,4-bis (1-isocyanato-1-methylethyl) benzene, ω, ω'-. Diisocyanato-1,4-diethylbenzene and the like can be mentioned, and mixtures thereof can also be used.

The hydroxyl group-containing compound used in the first step is not particularly limited, and examples thereof include compounds containing one or more hydroxyl groups in one molecule. Examples of such hydroxyl group-containing compounds include methanol, ethanol, propanol, n-butanol, isobutanol, n-pentanol, 2-pentanol, n-hexanol, 2-hexanol, n-heptanol, n-octanol, and the like. 2-Ethyl-1-hexanol, 3,3,5-trimethyl-1-hexanol, n-tridecanol, 2-tridecanol, 2-octyldodecanol, pentadecanol, palmityl alcohol, stearyl alcohol, cyclopentanol, cyclo Examples thereof include monoalcohols such as hexanol, methylcyclohexanol and trimethylcyclohexanol, and alcandiols of C2 to C18.

The catalyst used in the reaction can be appropriately selected from known catalysts and used depending on the reaction to be carried out. For example, a quaternary ammonium salt or the like can be used as the isocyanurate-forming catalyst, and a basic catalyst such as a carboxylic acid metal salt or the like can be used as the allophanate-forming catalyst.

Examples of the quaternary ammonium salt include 2-hydroxypropyltrimethylammonium octylate (DABCO TMR, manufactured by Sankyo Air Products Co., Ltd.), tetramethylammonium acetate, tetrabutyltylammonium acetate and the like as commercially available products. ..

Examples of the carboxylic acid metal salt include zinc salts, tin salts and zirconium salts of carboxylic acids such as acetic acid, propionic acid, undecylic acid, capric acid, octyl acid and myristyl acid.

The first step reaction can also be carried out in various organic solvents that do not affect the reaction, and examples of the organic solvent include, for example, aliphatic hydrocarbons, alicyclic hydrocarbons, ketones, esters and glycols. Examples thereof include ether esters, ethers, halogenated hydrocarbons, polar aproton solvents and the like.

Examples of aliphatic hydrocarbons include n-hexane and octane.

Examples of alicyclic hydrocarbons include cyclohexane and methylcyclohexane.

Examples of the ketones include acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and the like.

Examples of the esters include methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate and the like.

Examples of glycol ether esters include ethylene glycol ethyl ether acetate, propylene glycol methyl ether acetate, 3-methyl-3-methoxybutyl acetate, ethyl-3-ethoxypropionate and the like.

Examples of ethers include diethyl ether, tetrahydrofuran, dioxane and the like.

Examples of halogenated hydrocarbons include methyl chloride, methylene chloride, chloroform, carbon tetrachloride, methyl bromide, methylene iodide, dichloroethane and the like.

Examples of the polar aprotic solvent include N-methylpyrrolidone, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, hexamethylphosphonylamide and the like.

These solvents can be used alone or in combination of two or more.

The organic solvent used in the reaction is removed at the same time as the removal of the free organic diisocyanate in the fourth step.

The reaction terminator in the second step has an action of inactivating the activity of the catalyst, and specifically, an organic acid having an inorganic acid such as phosphoric acid or hydrochloric acid, a sulfonic acid group, or a sulfamic acid group. And known compounds such as these esters and acyl halides are used. These reaction terminators can be used alone or in combination of two or more. It is preferable that the addition time is prompt after the reaction is completed.

The amount of the reaction terminator added varies depending on the type of the reaction terminator and the catalyst used, but is preferably 0.5 to 10 equivalents of the catalyst, and 0.8 to 5.0 equivalents is particularly preferable. If the amount of the reaction terminator is small, the storage stability of the obtained polyisocyanate composition tends to decrease, and if it is too large, the modified polyisocyanate may be colored.

Examples of the compound having a sterically hindered phenol structure other than BHT added in the third step include tetrakis [methylene-3- (3', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane. , 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propanoate octadecyl, 3- (4-hydroxy-3,5-diisopropylphenyl) propionate octyl, 1,3,5-tris (3) , 5-Di-tert-butyl-4-hydroxybenzyl) isocyanuric acid, 2,4,6-tris (3', 5'-di-tert-butyl-4'-hydroxybenzyl) mecitylene and the like. In addition, compounds having a sterically hindered phenol structure that can be obtained under the trade name of IRGANOX (manufactured by BASF) and those available under the trade name of ADEKA STAB (manufactured by Adeka) are also included.

In the present invention, adding a compound having a sterically hindered phenolic structure other than BHT after producing a modified organic polyisocyanate means this third step, and is added after stopping the reaction in the second step.

In the purification step of the fourth step, the free unreacted organic diisocyanate monomer present in the reaction mixture is removed by a thin film distillation method or an organic solvent at 120 to 150 ° C. under a high vacuum of, for example, 10 to 100 Pa. The residual content is reduced to 1.0% by mass or less by the extraction method. If the residual content of the organic diisocyanate monomer exceeds the upper limit, odor may be generated and the storage stability may be lowered.

The modified organic polyisocyanate obtained by purification can be made into a blocked isocyanate by using a known blocking agent for the purpose of extending the pot life and liquefying the coating composition. As a result, the blocked polyisocyanate is inactive at room temperature, but the blocking agent is dissociated by heating, and the isocyanate group is activated again, which has a potential function of reacting with the active hydrogen group. Can be added.

The blocking agent that can be used in the present invention is a compound having one active hydrogen group in the molecule, for example, alcohol-based, alkylphenol-based, phenol-based, active methylene, mercaptan-based, acid amide-based, and acid imide. There are system, imidazole system, urea system, oxime system, amine system, imide system, pyrazole system compound and the like.

Further, the modified organic polyisocyanate obtained by a series of reactions can be mixed with a polyol to obtain the two-component coating composition of the present invention.

Here, the polyol used in the two-component coating composition of the present invention is not particularly limited, but is a compound containing an active hydrogen group as a reactive group with an isocyanate group, for example, a polyester polyol. Preferred are polyether polyols, polycarbonate polyols, polyolefin polyols, acrylic polyols, silicone polyols, castor oil-based polyols, fluorine-based polyols, ester exchanges of two or more types of polyols, and hydroxyl group-terminated prepolymers that have been urethanized with polyisocyanates. These can also be used as one kind or a mixture of two or more kinds.

<Polyester polyol>
Specific examples of polyester polyols include phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, succinic acid, tartaric acid, oxalic acid, malonic acid, glutaric acid, adipic acid, pimeric acid, suberic acid, glutaconic acid, and azelaic acid. , Sebacic acid, 1,4-cyclohexyldicarboxylic acid, α-hydromuconic acid, β-hydromuconic acid, α-butyl-α-ethylglutaric acid, α, β-diethylsuccinic acid, maleic acid, fumaric acid and other dicarboxylic acids One or more of acids or anhydrides thereof, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol , 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, 3,3-dimethylolheptan, diethylene glycol, Dipropylene glycol, neopentyl glycol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, diol dimerate, ethylene oxide or propylene oxide adduct of bisphenol A, bis (β-hydroxyethyl) benzene, xylyl Examples thereof include those obtained by a condensation reaction with one or more of low molecular weight polyols having a molecular weight of 500 or less, such as lenglycol, glycerin, trimethylolpropane, and pentaerythritol. In addition, lactone-based polyester polyols obtained from ring-open polymerization of cyclic ester (so-called lactone) monomers such as ε-caprolactone, alkyl-substituted ε-caprolactone, δ-valerolactone, and alkyl-substituted δ-valerolactone can be mentioned. Further, a polyester-amide polyol obtained by substituting a small molecule polyamine such as hexamethylenediamine, isophorone diamine, or monoethanolamine or a small molecule amino alcohol as a part of the small molecule polyol can also be used.

<Polyether polyol>
Specific examples of the polyether polyol include, for example, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1, 5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, 3,3-dimethylolheptan, diethylene glycol, dipropylene glycol , Neopentyl glycol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, dimer acid diol, bisphenol A, bis (β-hydroxyethyl) benzene, xylylene glycol, glycerin, trimethylolpropane, pentaerythritol 2 or more, preferably 2 to 3 active hydrogen groups such as low molecular weight polyols such as ethylenediamine, propylenediamine, toluenediamine, metaphenylenediamine, diphenylmethanediamine, and low molecular weight polyamines such as xylylene diamine. Polyether polyols obtained by addition polymerization of alkylene oxides such as ethylene oxide, propylene oxide, butylene oxide, etc., or alkyl glycidyl ethers such as methyl glycidyl ether, phenyl glycidyl ether, etc. Examples thereof include aryl glycidyl ethers, polyether polyols obtained by ring-opening polymerization of cyclic ether monomers such as tetrahydrofuran, and the like.

<Polycarbonate polyol>
Specific examples of the polycarbonate polyol include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, and 1,5. -Pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, 3,3-dimethylol heptane, diethylene glycol, dipropylene glycol, Neopentyl glycol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, dimeratediol, ethylene oxide and propylene oxide adducts of bisphenol A, bis (β-hydroxyethyl) benzene, xylylene glycol, glycerin , Trimethylol propane, pentaerythritol and other low molecular weight polyols, dialkyl carbonates such as dimethyl carbonate and diethyl carbonate, alkylene carbonates such as ethylene carbonate and propylene carbonate, diphenyl carbonate, dinaphthyl carbonate and dianthryl carbonate. , Diphenolyl carbonate, diindanyl carbonate, tetrahydronaphthyl carbonate and other diaryl carbonates, and those obtained from dealcoholization reaction and dephenolization reaction can be mentioned.

Further, a polyol obtained by transesterification reaction of a polycarbonate polyol, a polyester polyol and a small molecule polyol can also be preferably used.

<Polyolefin polyol>
Specific examples of the polyolefin polyol include polybutadiene having two or more hydroxyl groups, hydrogenated polybutadiene, polyisoprene, hydrogenated polyisoprene and the like.

<Acrylic polyol>
Examples of the acrylic polyol include an acrylic acid ester and / or a methacrylic acid ester [hereinafter referred to as (meth) acrylic acid ester], and an acrylic acid hydroxy compound having at least one hydroxyl group in the molecule which can be a reaction point and / or methacryl. Examples thereof include those obtained by copolymerizing an acid-hydroxy compound [hereinafter referred to as (meth) acrylic acid hydroxy compound] and a polymerization initiator with an acrylic monomer using heat energy, light energy such as ultraviolet rays or electron beams, and the like. ..

<(Meta) acrylic acid ester>
Specific examples of the (meth) acrylic acid ester include alkyl esters having 1 to 20 carbon atoms. Specific examples of such (meth) acrylic acid ester include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, and pentyl (meth) acrylate. , (Meta) hexyl acrylate, (meth) -2-ethylhexyl acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, etc. Acrylic acid alkyl ester, ester of (meth) acrylic acid with alicyclic alcohol such as cyclohexyl (meth) acrylate, (meth) acrylic acid aryl ester such as (meth) phenyl acrylate, benzyl (meth) acrylate, etc. Can be mentioned. Such (meth) acrylic acid esters may be used alone or in combination of two or more.

<(Meta) hydroxy acrylate compound>
Specific examples of the (meth) hydroxyacrylate compound include at least one hydroxyl group in the molecule that can serve as a reaction point with polyisocyanate, and specifically, for example, 2-hydroxyethyl acrylate, 2-. Examples thereof include hydroxyacrylate compounds such as hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 3-hydroxy-2,2-dimethylpropyl acrylate, and pentaerythritol triacrylate. Examples thereof include hydroxymethacrylic acid compounds such as 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, 3-hydroxy-2,2-dimethylpropyl methacrylate and pentaerythritol trimethacrylate. These (meth) hydroxy acrylate compounds may be used alone or in combination of two or more.

<Silicone polyol>
Specific examples of the silicone polyol include, for example, a vinyl group-containing silicone compound obtained by polymerizing γ-methacryloxypropyltrimethoxysilane, etc., and α, ω-dihydroxypolydimethylsiloxane, α having at least one terminal hydroxyl group in the molecule. , Ω-Dihydroxypolydiphenylsiloxane, and other polysiloxanes.

<Castor oil-based polyol>
Specific examples of castor oil-based polyols include linear or branched polyester polyols obtained by reacting castor oil fatty acids with polyols. Further, dehydrated castor oil, partially dehydrated partially dehydrated castor oil, and hydrogenated castor oil can also be used.

<Fluorine-based polyol>
Specific examples of the fluorine-based polyol are linear or branched polyols obtained by a copolymerization reaction containing, for example, a fluorine-containing monomer and a monomer having a hydroxy group as essential components. Here, the fluorine-containing monomer is preferably a fluoroolefin, for example, tetrafluoroethylene, chlorotrifluoroethylene, trichlorofluoroethylene, hexafluoropropylene, vinylidene fluoride, vinyl fluoride, trifluoromethyltrifluoroethylene. And so on. Examples of the monomer having a hydroxyl group include hydroxyalkyl vinyl ethers such as hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether and cyclohexanediol monovinyl ether, hydroxyalkyl allyl ethers such as 2-hydroxyethyl allyl ether, and vinyl hydroxyalkyl crotonates. Examples thereof include monomers having a hydroxyl group such as a hydroxyl group-containing vinyl carboxylate or an allyl ester.

Further, the polyol preferably has an active hydrogen group number (average number of functional groups) of 1.9 to 6.0 in one molecule. If the number of active hydrogen groups is less than the lower limit, the physical properties of the coating film may deteriorate. Further, if it exceeds the upper limit value, the adhesion may be lowered.

The number average molecular weight of the polyol is preferably in the range of 750 to 50,000. If it is less than the lower limit value, the adhesion may be lowered, and if it exceeds the upper limit value, the solubility in a low-polarity organic solvent may be lowered or the adhesion may be lowered.

The mixing ratio of the polyisocyanate composition of the two-component coating composition of the present invention and the polyol is not particularly limited, but the molar ratio of the isocyanate group in the isocyanate composition to the hydroxyl group in the polyol is determined. It is preferable to mix so that R = isocyanate group / hydroxyl group is 0.5 to 2.5. If it is less than the lower limit, the number of hydroxyl groups becomes excessive, which may lead to a decrease in adhesion. In addition, the crosslink density may decrease, the durability may decrease, and the mechanical strength of the coating film may decrease. If it exceeds the upper limit, the isocyanate group becomes excessive and reacts with the moisture in the air, which may cause swelling of the coating film and a decrease in adhesion due to the swelling.

Examples of the organic solvent used as the diluting solvent include ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, esters such as ethyl acetate, butyl acetate and cellosolve acetate, alcohols such as butanol and isopropyl alcohol, toluene and xylene. From the group consisting of hydrocarbons such as cyclohexane, mineral spirit, and naphtha, it can be appropriately selected and used according to the purpose and application. These solvents may be used alone or in combination of two or more.

Further, in the two-component coating composition of the present invention, a known urethanization catalyst can be appropriately used in consideration of pot life, curing conditions, working conditions and the like. Specifically, an organic metal compound such as dibutyltin diacetate, dibutyltin dilaurate, or dioctyltin dilaurate, an organic amine such as triethylenediamine or triethylamine, or a salt thereof is selected and used. These catalysts can be used alone or in combination of two or more.

The curing conditions of the two-component coating composition of the present invention are not particularly limited, but the curing temperature is −5 to 120 ° C., the humidity is 10 to 95% RH, and the curing time is 0.5 to 5. It is preferably 168 hours.

The two-component coating composition obtained by the present invention is applied onto the surface of an adherend by a known method such as spraying, brushing, dipping, or coating to form a coating film.

Here, the adherend is not particularly limited, and stainless steel, phosphoric acid-treated steel, zinc steel, iron, copper, aluminum, brass, glass, slate, acrylic resin, polycarbonate resin, polyethylene terephthalate resin, and polyethylene naphthalate. Resin, polybutylene phthalate resin, polystyrene resin, AS resin, ABS resin, polycarbonate-ABS resin, 6-nylon resin, 6,6-nylon resin, MXD6 nylon resin, polyvinyl chloride resin, polyvinyl alcohol resin, polyurethane resin, phenol Adhesion molded from materials such as resin, melamine resin, polyacetal resin, chlorinated polyolefin resin, polyolefin resin, polyamide resin, polyether ether ketone resin, polyphenylene sulfide resin, NBR resin, chloroprene resin, SBR resin, SEBS resin, etc. , An olefin resin such as polyethylene or polypropylene that has been subjected to corona discharge treatment or other surface treatment, or an adherend having an intermediate layer such as a primer layer formed on the surface of the adherend can be used.

Since the film thickness of the coating film formed on the surface layer of the adherend is excellent in recoatability and durability, a film thickness of at least 10 μm may be formed on the adherend. If the film thickness is less than 10 μm, the durability is lowered, and the coating film may be torn due to impact.

Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited to the following Examples. The% notation in the examples is based on mass unless otherwise specified.

<Synthesis of polyisocyanate composition>
<Example 1>
Hexamethylene diisocyanate (NCO content: 49.9% by mass, manufactured by Tosoh Corporation, hereinafter referred to as HDI) in a 4-necked flask with a capacity of 1 liter equipped with a stirrer, a thermometer, a cooling tube, and a nitrogen gas introduction tube, and 985 g. 15 g of n-octanol (manufactured by Sanyo Kasei Kogyo Co., Ltd.) was charged, and these were heated to 60 ° C. with stirring to carry out a urethanization reaction for 1 hour. Then, 1 g of trimethyloctylammonium methylcarbonate (diluted by 10% 2-ethylhexanol, manufactured by Koei Kagaku Co., Ltd.), which is an isocyanurate-forming catalyst, is used in this reaction solution until a predetermined reaction conversion rate is reached at 60 ° C. After the reaction, 0.17 g of an acidic phosphoric acid ester (JP-508, manufactured by Johoku Chemical Industry Co., Ltd.) as a reaction terminator was added, and the terminator reaction was carried out at 60 ° C. for 1 hour. Here, 0.1 g of tetrakis [methylene-3- (3', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane (IRGANOX 1010, manufactured by BASF) was added, and 1 at 60 ° C. Stir and mix for hours. Then, excess HDI was removed from the reaction product by thin film distillation (conditions: 140 ° C., 0.04 kPa) to obtain 400 g of modified organic polyisocyanate P-1.

<Examples 2 and 3, Comparative Example 1>
Synthesis was carried out under the conditions shown in Table 1, and modified polyisocyanates P-2, P-3, and P-4 were obtained in the same procedure as in Example 1.

<Comparative example 2>
HDI (NCO content: 49.9% by mass, manufactured by Tosoh Corporation) 985 g, and n-octanol (Sanyo Kasei) in a 1-liter capacity four-necked flask equipped with a stirrer, thermometer, cooling tube, and nitrogen gas introduction tube. 15 g (manufactured by Kogyo Co., Ltd.), 0.1 g of tetrakis [methylene-3- (3', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane (IRGANOX 1010, manufactured by BASF) were charged, and these were charged. Was heated to 60 ° C. with stirring, and a urethanization reaction was carried out for 1 hour. Then, 1 g of trimethyloctylammonium methylcarbonate (diluted by 10% 2-ethylhexanol, manufactured by Koei Chemical Co., Ltd.), which is an isocyanurate-forming catalyst, is used in this reaction solution until a predetermined reaction conversion rate is reached at 60 ° C. After the reaction, 0.17 g of an acidic phosphoric acid ester (JP-508, manufactured by Johoku Chemical Industry Co., Ltd.) as a reaction terminator was added, and the terminator reaction was carried out at 60 ° C. for 1 hour. Then, excess HDI was removed from the reaction product by thin film distillation (conditions: 140 ° C., 0.04 kPa) to obtain 400 g of modified organic polyisocyanate P-5.

<Comparative Examples 3 to 5>
Synthesis was carried out under the conditions shown in Table 1, and modified polyisocyanates P-6, P-7, and P-8 were obtained in the same procedure as in Comparative Example 2.

The raw materials used in Table 1 are as follows.
-Acid phosphate: Di-2-ethylhexyl phosphate (JP-508, manufactured by Johoku Chemical Industry Co., Ltd.)
-Catalyst-1: trimethyloctylammonium methyl carbonate (manufactured by Koei Chemical Industry Co., Ltd.)
PHA-1: Tetrakis [methylene-3- (3', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane (IRGANOX 1010, manufactured by BASF)
PHA-2: 3- (3,5-di-tert-butyl-4-hydroxyphenyl) octadecyl propanoate (IRGANOX 1076, manufactured by BASF)
PHA-3: 3- (4-hydroxy-3,5-diisopropylphenyl) octyl propionate (IRGANOX 1135, manufactured by BASF)
-PHA-4: 2,6-di-tert-butyl-4-methylphenol (H-BHT, manufactured by Honshu Chemical Industry Co., Ltd.).

The timing of addition of the compound having a sterically hindered phenol structure in Table 1 is described as "after" when the antioxidant is added after the formation of the modified organic polyisocyanate and "before" when the compound is added before the formation.

<Evaluation of number of colors>
For the evaluation of the number of colors, the method of the number of Hazen unit colors (platinum-cobalt scale) shown in JIS K 0071-1 was used.

<Solvent dilution stability>
<Initial value>
The obtained modified organic polyisocyanates P-1 to P-8 were diluted with methyl ethyl ketone (MEK) so as to have a solid content of 20%, and the number of colors thereof was measured.

<50 ° C x 3 months later>
The modified organic polyisocyanates P-1 to P-8 diluted in MEK to a solid content of 20% were stored at 50 ° C. for 3 months, and then the number of colors was measured.

In each example, no significant change was observed in the number of colors of the modified organic polyisocyanates P-1 to P-3 diluted with MEK after storage at 50 ° C. for 3 months.

Claims (6)

In the method for producing a modified organic polyisocyanate in which an organic diisocyanate monomer is isocyanurate or allophanate.
First step: The organic diisocyanate monomer and the hydroxyl group-containing compound are blended so that the isocyanate group is excessive in the molar ratio with respect to the hydroxyl group.
A step of producing an isocyanate group-terminated prepolymer by subjecting at least one of the isocyanurate-forming and allophanation-forming reactions to each other.
Second step: A step of stopping the reaction,
Third step: A step of adding a compound having a sterically hindered phenol structure (excluding 2,6-di-tert-butyl-4-methylphenol).
Fourth step: A step of obtaining a modified organic polyisocyanate from the isocyanate group-terminated prepolymer obtained in the third step by thin film distillation or solvent extraction.
Including
A method for producing a modified organic polyisocyanate, wherein the organic diisocyanate monomer is at least one selected from an aliphatic diisocyanate and an alicyclic diisocyanate. Compounds with a sterically hindered phenolic structure are tetrakis [methylene-3- (3', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane, 3- (3,5-di-tert-butyl). Octadecyl propanate (-4-hydroxyphenyl), octyl 3- (4-hydroxy-3,5-diisopropylphenyl) propionate, 1,3,5-tris (3,5-di-tert-butyl-4-hydroxybenzyl) ) Isocyanuric acid, 2,4,6-tris (3', 5'-di-tert-butyl-4'-hydroxybenzyl) according to claim 1, characterized in that it is at least one selected from mesitylene. Method for producing modified organic polyisocyanate. The method for producing a modified organic polyisocyanate according to claim 1 or 2, wherein the modified organic polyisocyanate is a modified product of hexamethylene diisocyanate. The method for producing a modified organic polyisocyanate according to any one of claims 1 to 3, wherein the modified organic polyisocyanate contains at least one selected from the group consisting of an isocyanurate group and an allophanate group. A method for producing a two-component coating composition containing the modified organic polyisocyanate obtained by the production method according to any one of claims 1 to 4 and a polyol. A method for producing a coating film obtained from the two-component coating composition obtained by the production method according to claim 5.