JP5499474B2 - Curing agent composition for two-component curable paint - Google Patents

Description

  The present invention relates to a curing agent composition for a two-component curable coating material.

Two-component curable urethane coatings that use polyisocyanate as a component provide coatings with excellent weather resistance and abrasion resistance. Conventionally, coating of outdoor substrates such as buildings and civil engineering structures, It is used for repair and plastic coating.
Because of the high polarity of polyisocyanate, this paint generally uses strong solvents such as aromatic hydrocarbon solvents such as toluene and xylene, and ester solvents such as butyl acetate, that is, solvents with strong dissolving power. It was done.

  Since these strong solvents have a strong odor, they tend to be avoided in recent years in terms of improving the working environment and reducing the burden on the global environment. In addition, when repairing or repainting a new coating over the old paint film, if the repair paint contains a strong solvent with high solubility, the old paint film will swell or dissolve, There is a possibility that the film needs to be repaired. As a result, problems such as enlargement and complication of painting work, increase in painting cost, and extension of construction period may occur.

In view of the above points, in recent years, polyisocyanates that are easily soluble in low-polar organic solvents have been developed.
For example, in Patent Document 1 (Japanese Patent Laid-Open No. 8-198928), as a polyisocyanate excellent in dilutability with a low polar organic solvent, dilutability with an alicyclic diisocyanate and a low polar organic solvent is 100% or more. Polyisocyanates obtained by reacting with polyols are disclosed.

  Patent Document 2 (Japanese Patent Laid-Open No. 2008-24828) discloses an aliphatic and / or alicyclic diisocyanate and a carbon number of 1 as a polyisocyanate having excellent solubility in a low-polar organic solvent and compatibility with a silicate compound. Polyisocyanate compounds obtained from ˜20 monoalcohols and having a predetermined allophanate group / isocyanurate group molar ratio and a predetermined molecular weight distribution are disclosed.

  These polyisocyanates of Patent Documents 1 and 2 have good solubility in an organic solvent having an aniline point of 10 to 70 ° C, but are soluble in an organic solvent having a lower solubility such that the aniline point exceeds 70 ° C. There is room for improvement.

JP-A-8-198928 JP 2008-24828 A

  The present invention has been made in view of the above circumstances, and is for a two-component curable coating that can provide a coating film with good solvent resistance while being soluble in an organic solvent having an aniline point exceeding 70 ° C. It aims at providing a hardening | curing agent composition.

  As a result of intensive investigations to achieve the above object, the present inventors have found that allophanate groups / isocyanurate groups in polyisocyanates obtained by reacting aliphatic diisocyanates with alkyl monools having 11 or more carbon atoms. By setting the molar ratio within a predetermined range, solubility in a low-polar organic solvent having an aniline point exceeding 70 ° C. is improved, and a curing agent and a polyol containing the polyisocyanate and a solvent having an aniline point exceeding 70 ° C. The coating film obtained from the coating material containing it discovered that solvent resistance was also favorable, and completed this invention.

That is, the present invention
1. Comprising a polyisocyanate (A) and an organic solvent (B) having an aniline point of more than 70 ° C.,
The polyisocyanate (A) includes a product in which an aliphatic diisocyanate and an alkyl monool having 11 or more carbon atoms are reacted in the presence of tin octylate to form allophanate groups and isocyanurate groups substantially simultaneously. A two-part curing type curing agent composition for paints, comprising allophanate groups and isocyanurate groups in an allophanate group / isocyanurate group = 95/5 to 65/35 (molar ratio),
2. 1 two-component curable coating composition for paint containing the allophanate group and isocyanurate group in an allophanate group / isocyanurate group = 95/5 to 68/32 (molar ratio) ;
3. 1 or 2 two-component curable curing agent composition for paint, wherein the alkyl monool is an alkyl monool having 11 to 20 carbon atoms,
4). The two-component curable coating composition for a coating composition according to any one of 1 to 3, wherein the aliphatic diisocyanate is hexamethylene diisocyanate.

The curing agent composition for two-component curable coatings of the present invention is excellent in solubility in an organic solvent (weak solvent) having an aniline point exceeding 70 ° C., and is also a fluorine-based or acrylic-based one used in two-component coatings. Good compatibility with polyols.
Moreover, the coating film obtained from the two-component coating composition using this polyisocyanate composition also has good solvent resistance.
Furthermore, since the two-component curable coating composition containing the two-component curable coating composition of the present invention can use a low-polar organic solvent (weak solvent) as a solvent, the base layer is eroded when repeatedly applied. The recoatability is excellent.

Hereinafter, the present invention will be described in more detail.
The curing agent composition for a two-component curable coating material according to the present invention includes a polyisocyanate (A) and an organic solvent (B) having an aniline point of more than 70 ° C., and the polyisocyanate (A) contains an aliphatic diisocyanate and a carbon number. It is obtained by reacting 11 or more alkyl monools, and contains allophanate groups and isocyanurate groups in an allophanate group / isocyanurate group = 95/5 to 65/35 (molar ratio).

In this invention, when the allophanate group in polyisocyanate exceeds 95 mol%, the solvent resistance of the coating film obtained using the hardening | curing agent of this invention will fall. On the other hand, if it is less than 65 mol%, the solubility in a solvent having an aniline point exceeding 70 ° C. is lowered.
The allophanate group / isocyanurate group (molar ratio) is preferably 95/5 to 68/32, more preferably 95/5 to 70/30.
The molar ratio of each functional group can be calculated by ¹ H-NMR measurement.

As said polyisocyanate, what made allophanate and / or isocyanurate the aliphatic diisocyanate and C11 or more alkyl monool can be used.
In this case, the aliphatic diisocyanate can be appropriately selected from conventionally known ones, such as hexamethylene diisocyanate, 1,4-tetramethylene diisocyanate, 2-methylpentane-1,5-diisocyanate, and lysine diisocyanate. Etc. can be used. These diisocyanates may be used alone or in combination of two or more.
Among these, hexamethylene diisocyanate is preferable in view of further improving the solvent resistance of the resulting coating film.

  Specific examples of alkyl monools having 11 or more carbon atoms include isotridecanol, 1-undecanol, 1-dodecanol, 1-eicosanol, 1-heptadecanol, 1-nonadecanol, 1-tridecanol, 1-tetradecanol. 1-pentadecanol, stearyl alcohol, isostearyl alcohol, 3-ethyl-4,5,6-trimethyloctanol, 4,5,6,7-tetramethylnonanol, 4,5,8-trimethyldecanol, 4,7,8-trimethyldecanol, 2-hexyldodecanol, 2-octyldodecanol, 2-dodecyldecanol, 2-hexadecyloctadecanol and the like.

  Among these, in view of further increasing the solubility of the resulting polyisocyanate in an organic solvent having an aniline point of more than 70 ° C., alkyl monools having 11 to 20 carbon atoms are preferred, and in particular, 1-tridecanol, isotriol Preferred are decanol, 1-dodecanol, 1-eicosanol, 1-heptadecanol, 1-nonadecanol, 1-tetradecanol, 1-pentadecanol, stearyl alcohol, isostearyl alcohol, 1-tridecanol, isotridecanol Is more preferable.

The allophanatization reaction can be performed by heating the polyisocyanate and alcohol as described above to about 50 to 150 ° C. in the presence or absence of an organic solvent.
Allophanatization may be performed simultaneously with urethanization or after urethanization. When urethanization and allophanatization are performed simultaneously, the reaction may be performed in the presence of an allophanatization catalyst. When allophanatization is performed after urethanization, the urethanization reaction was performed for a predetermined time in the absence of the allophanatization catalyst. Thereafter, an allophanatization catalyst may be added to carry out the allophanatization reaction.

The allophanatization catalyst can be appropriately selected from known catalysts, and for example, a zirconium salt of a carboxylic acid can be used. Examples of the carboxylic acid include saturated aliphatic carboxylic acids such as acetic acid, propionic acid, butyric acid, caproic acid, octylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, 2-ethylhexanoic acid, cyclohexanecarboxylic acid, Saturated monocyclic carboxylic acids such as cyclopentanecarboxylic acid, saturated polycyclic carboxylic acids such as bicyclo (4.4.0) decane-2-carboxylic acid, mixtures of the above-mentioned carboxylic acids such as naphthenic acid, oleic acid, linoleic acid , Monocarboxylic acids such as unsaturated aliphatic carboxylic acids such as linolenic acid, soybean oil fatty acid and tall oil fatty acid, aromatic aliphatic carboxylic acids such as diphenylacetic acid, aromatic carboxylic acids such as benzoic acid and toluic acid; phthalic acid, Isophthalic acid, terephthalic acid, naphthalene dicarboxylic acid, succinic acid, tartaric acid, oxalic acid, malonic acid, gluta Acid, adipic acid, pimelic acid, suberic acid, curtaconic acid, azelaic acid, sebacic acid, 1,4-cyclohexyldicarboxylic acid, α-hydromuconic acid, β-hydromuconic acid, α-butyl-α-ethylglutaric acid, Examples thereof include polycarboxylic acids such as α, β-diethylsuccinic acid, maleic acid, fumaric acid, trimellitic acid and pyromellitic acid. These zirconium carboxylates can be used alone or in combination of two or more. In particular, it is more preferable to use a monocarboxylic acid zirconium salt having 10 or less carbon atoms such as zirconium octylate and zirconium 2-ethylhexanoate.
In addition, 0.0005-1 mass% is preferable with respect to the total mass of polyisocyanate and alcohol, and, as for the usage-amount of an allophanatization catalyst, 0.001-0.1 mass% is more preferable.

  When the reaction is performed in the presence of an organic solvent, various organic solvents that do not affect the reaction can be used. Specific examples thereof include aliphatic hydrocarbons such as n-hexane and octane; cyclohexane, methylcyclohexane, and the like. Alicyclic hydrocarbons; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone; esters such as methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate; ethylene glycol ethyl ether acetate, propylene glycol methyl ether acetate, Glycol ether esters such as 3-methyl-3-methoxybutyl acetate and ethyl-3-ethoxypropionate; ethers such as diethyl ether, tetrahydrofuran and dioxane; methyl chloride, methylene chloride, chloroform and tetrasalt Carbon, methyl bromide, methylene iodide, halogenated hydrocarbons dichloroethane; N- methylpyrrolidone, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, polar aprotic solvents such as hexamethylphosphoric phosphonyl amides. These solvents can be used alone or in combination of two or more.

After completion of the reaction, a reaction terminator such as phosphoric acid or phosphoric acid ester is added to the reaction system, and a termination reaction is performed at 30 to 100 ° C. for 1 to 2 hours to terminate the allophanate reaction.
After termination of the reaction, the desired allophanate-modified polyisocyanate can be obtained by removing unreacted components by a known method such as thin film distillation.
The obtained allophanate-modified polyisocyanate can be used as it is (when it satisfies the above-mentioned allophanate group / isocyanurate group range).

The allophanate-modified polyisocyanate obtained as described above mainly has an allophanate group, but a side reaction occurs due to, for example, a reaction under a condition in which an isocyanate group is excessively present, and an isocyanurate group is generated.
Therefore, the molar ratio of allophanate groups and isocyanurate groups in the obtained polyisocyanate is adjusted to 95/5 to 65/35 by appropriately adjusting various conditions such as the ratio of [NCO] / [OH] in allophanatization. It can adjust suitably in the range.

  On the other hand, examples of the isocyanuration reaction include a method of modifying (trimerization) polyisocyanate in the presence of an isocyanuration catalyst. As such a modification method, for example, methods described in Japanese Patent Nos. 3371480 and 2002-241458 can be used.

Examples of the isocyanurate-forming catalyst include metal salts of aliphatic carboxylic acids, phenolates such as potassium phenolate, 2,4,6-tris (dimethylaminomethyl) phenol, 2,4-bis (dimethylaminomethyl) phenol, Amine systems such as 2,6-di-t-butyl-4-dimethylaminotrimethylsilanephenol, triethylamine, N, N ′, N ″ -tris (dimethylaminopropyl) hexahydro-S-triazine, diazabicycloundecene Compounds can be used. Among these, tin salts, potassium salts, sodium salts, calcium salts, zinc salts, and bismuth salts of aliphatic carboxylic acids are preferable, and tin salts are particularly preferable because of easy reaction control.
Specifically, a tin salt of acetic acid, propionic acid, undecylic acid, capric acid, octylic acid, and myristic acid can be suitably used. In particular, tin octylate is most suitable.
In addition, 2-hydroxypropyltrimethylammonium octylate (DABCO TMR, manufactured by Sankyo Air Products Co., Ltd.) and potassium octylate (DABCO K-15, manufactured by Sankyo Air Products Co., Ltd.) may be used as commercially available products. it can.
In addition, 0.0005-1 mass% is preferable with respect to the total mass of polyisocyanate and alcohol, and, as for the usage-amount of an isocyanurate-ized catalyst, 0.001-0.1 mass% is more preferable.

The isocyanurate-modified polyisocyanate obtained as described above has an isocyanurate group, but also has an allophanate group by-produced during the reaction.
The molar ratio of the allophanate group and the isocyanurate group in the obtained isocyanurate-modified polyisocyanate can be adjusted in the range of 95/5 to 65/35 by appropriately adjusting the isocyanurate reaction time and the like.
The allophanate-modified polyisocyanate obtained by allophanate conversion may be further isocyanurated to adjust the allophanate group / isocyanurate group molar ratio to the above range.

The polyisocyanate used in the present invention may be a blend of allophanate-modified polyisocyanate and isocyanurate-modified polyisocyanate.
In this case, allophanate-modified polyisocyanate and isocyanurate-modified polyisocyanate may be mixed at a ratio satisfying the above-described allophanate group / isocyanurate group molar ratio.
In addition, as long as the molar ratio of the allophanate group and isocyanurate group mentioned above is satisfy | filled as the whole mixture, the polyisocyanate which does not satisfy | fill the molar ratio of the said allophanate group and isocyanurate group can also be used partially.

  By the various methods described above, the polyisocyanate of the present invention in which the molar ratio of allophanate groups and isocyanurate groups is adjusted to the above range can be obtained. In the present invention, the reaction is easily controlled and the solubility is improved. In the isocyanuration reaction using tin octylate as a catalyst, the isocyanurate group and the allophanate group are substantially adjusted by appropriately adjusting the reaction time in the isocyanuration reaction using tin octylate as a catalyst. It is preferable to use a method of generating them simultaneously (in a one-step reaction).

  The viscosity of the polyisocyanate used in the present invention is not particularly limited, but is preferably 2,000 mPa · s or less at 25 ° C., more preferably 1,500 mPa · s or less, and 1,000 mPa. -More preferably, it is s or less. If the viscosity of the polyisocyanate exceeds 2,000 mPa · s, the viscosity of the coating composition may increase and it may be difficult to handle. On the other hand, the lower limit of the viscosity is not particularly limited, but is preferably 50 mPa · s or more, more preferably 100 mPa · s, and even more preferably 200 mPa · s from the viewpoint of handling.

Moreover, the curing agent composition for a two-component curable paint of the present invention contains an organic solvent having an aniline point of more than 70 ° C.
Here, the “aniline point” is a minimum temperature at which an equal volume of aniline and a sample (organic solvent) exist as a uniform mixed solution. The aniline point can be measured according to the aniline point test method described in JIS K 2256.
In addition, an organic solvent having an aniline point of more than 70 ° C. has a feature that there is little odor. Therefore, the hardening | curing agent composition of this invention containing such an organic solvent will be excellent also from an environmental viewpoint.
Furthermore, since such an organic solvent has a low dissolving power and does not easily attack the base, the coating composition can be repeatedly applied, and is suitable for a repair coating.

  Since the above-mentioned polyisocyanate of the present invention has good solubility in a solvent having low solubility, the aniline point is not particularly limited as long as it exceeds 70 ° C. However, if it is too high, the polyisocyanate of the present invention is not limited. Even if it is an isocyanate, since solubility falls, the upper limit is preferable about 100 degreeC, about 90 degreeC is more preferable, and about 85 degreeC is much more preferable.

  Examples of such organic solvents include IP solvent 1620 (aniline point 81 ° C.), IP solvent 1016 (aniline point 72 ° C.), IP solvent 2028 (aniline point 89 ° C.), IP solvent 2835 (aniline point 104 ° C.) ( As described above, manufactured by Idemitsu Kosan Co., Ltd., Shellsol S (manufactured by Shell Chemicals Japan Co., Ltd., aniline point 78 ° C.), Isopar G (manufactured by ExxonMobil Co., Ltd., aniline point 78 ° C.), Nisseki Isosol 300 (New Japan) Petrochemical Co., Ltd., aniline point 80 ° C.), normal paraffin SL (manufactured by Nippon Petrochemical Co., Ltd., aniline point 80 ° C.), Marcazole R (aniline point 88 ° C., manufactured by Maruzen Petrochemical Co., Ltd.), etc. Can be mentioned. These organic solvents can be used individually by 1 type or in mixture of 2 or more types.

  The blending ratio of the polyisocyanate and the organic solvent having an aniline point of more than 70 ° C. in the two-component curable coating composition is not particularly limited, but in the present invention, the polyisocyanate: Organic solvent = 90: 10 to 10:90 is preferable, and 80:20 to 20:80 is more preferable.

The curing agent composition for a two-component curable coating material of the present invention is used as a two-component curable coating material together with a polyol compound as a main component.
Here, it does not specifically limit as a polyol compound, What is necessary is just to select suitably from the polyol compounds generally used for the two-component curable coating material.
Specific examples include acrylic polyols, fluorine polyols, etc. Among them, fluorine polyols are preferable in consideration of weather resistance, and acrylic polyols are preferable in consideration of the balance between weather resistance and cost. is there.

  The acrylic polyol is not particularly limited, and a known acrylic polyol can be used. Specific examples thereof include commercially available products, such as ACRICID HU-596 (manufactured by DIC Corporation), EXCEROL 410 (manufactured by Asia Industry Co., Ltd.), and Hitaroid 6500 (manufactured by Hitachi Chemical Co., Ltd.). It is done.

  It does not specifically limit as a fluorine-type polyol, A well-known fluorine-type polyol can be used. Specific examples thereof include a fluoroethylene-vinyl ether (vinyl ester) copolymer. As a commercial item, Lumiflon LF800 (Asahi Glass Co., Ltd. product) etc. are mentioned.

The hydroxyl value and acid value of the polyol compound are not particularly limited, but in the coating composition of the present invention, the hydroxyl value is preferably 1 to 300 mgKOH / g, more preferably 1 to 250 mgKOH / g. preferable. When the hydroxyl value is less than 1 mg KOH / g, the coating film is insufficiently crosslinked, and the physical properties such as the coating film strength tend to decrease. The followability and flexibility to the substrate may be reduced.
On the other hand, the acid value is preferably from 0.1 to 5 mgKOH / g, and more preferably from 0.5 to 3 mgKOH / g.
The molecular weight of the polyol compound is not particularly limited, but the weight average molecular weight is preferably from 2,000 to 80,000, and particularly preferably from 10,000 to 50,000. When the weight average molecular weight is less than 2,000, the coating film may become brittle. When it exceeds 80,000, it may become difficult to dissolve in an organic solvent having an aniline point exceeding 70 ° C.
In addition, a weight average molecular weight is a measured value (polystyrene conversion value) by gel permeation chromatography (GPC) measurement by differential refractometer detection.

  The blending ratio of the curing agent composition and the polyol compound in the coating composition is preferably 1 to 150 parts by mass, and preferably 1 to 130 parts by mass with respect to 100 parts by mass of the polyol compound. Is more preferable, and it is more preferable that it is 1-100 mass parts.

  In addition, the said coating composition may contain the low polar organic solvent mentioned above and the various additives generally used for a coating material. Examples of additives include plasticizers, antiseptics, antifungal agents, algaeproofing agents, antifoaming agents, leveling agents, pigment dispersants, anti-settling agents, anti-sagging agents, catalysts, curing accelerators, dehydrating agents, and gloss. Examples include an eraser, an ultraviolet absorber, an antioxidant, a pigment, and a surfactant.

When producing a coating film from a coating composition using the curing agent of the present invention, brushing is applied to an appropriate base material such as concrete, mortar, siding board, extrusion board, porcelain tile, metal, glass, wood, plastic, etc. It may be applied by a method such as roller coating or spray coating, and dried and cured by an appropriate method.
Moreover, when coating a dry type building material, you may precoat in a factory etc. with a flow coater or a roll coater.
The coating composition may be applied directly to the base material, or may be applied from the top, electrodeposition, undercoating (primer coating), or intermediate coating (coloring, etc.). Moreover, when a base material is a metal, you may apply | coat after performing surface treatments, such as an iron phosphate process or a zinc phosphate process.

  EXAMPLES Hereinafter, although a synthesis example, an Example, and a comparative example are given and this invention is demonstrated more concretely, this invention is not limited to the following Example. In the following, “part” means “part by mass”.

[Synthesis Example 1] Synthesis of acrylic polyol IP solvent 1620 (aniline point 81 ° C., manufactured by Idemitsu Kosan Co., Ltd.) 715 was added to a reactor equipped with a stirrer, a thermometer, a cooling tube, a nitrogen gas introduction tube, and a dropping device. The temperature was raised to 115 ° C. while stirring. There, 710 parts of t-butyl methacrylate, 250 parts of lauryl methacrylate, 40 parts of 2-hydroxypropyl methacrylate, Kayaester-O (t-butyl-peroxy-2-ethylhexanoate, Kayaku Akzo ( A mixture consisting of 10 parts) and 100 parts of IP solvent 1620 was added dropwise over 4 hours. After completion of the dropwise addition, the mixture was reacted at the same temperature for 1 hour, and then a mixture composed of 10 parts of Kayaester-O and 205 parts of IP solvent 1620 was added dropwise over 1 hour. After completion of dropping, the mixture was reacted at the same temperature for 3 hours. The solid content was 50% by mass, the viscosity was 7,000 mPa · s (25 ° C.), the weight average molecular weight was 40,000, the hydroxyl value was 7.6 mgKOH / g, and the glass transition temperature was 39 ° C. A transparent hydroxyl group-containing acrylic polyol R-1 was obtained.

[1] Manufacture of curing agent composition for two-component curable coating material [Example 1] Synthesis of modified polyisocyanate S-1 Four 1 liter capacity equipped with stirrer, thermometer, cooler, and nitrogen gas inlet tube 880 g of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., NCO content: 49.9% by mass, hereinafter referred to as HDI) and 120 g of tridecanol were charged into a one-necked flask and heated to 85 ° C. with stirring. A time urethane reaction was carried out.
Thereafter, 0.15 g of tin octylate (manufactured by Nippon Chemical Industry Co., Ltd.), which is an isocyanurate-forming catalyst, was added to the reaction solution and reacted at 110 ° C., and the reaction was stopped when the predetermined NCO content was reached. 0.4 g of acidic phosphate ester (JP-508, manufactured by Johoku Chemical Industry Co., Ltd.) as an agent was added, and a stop reaction was performed at 50 ° C. for 1 hour.
Excess HDI was removed from this reaction product by thin film distillation (conditions: 140 ° C., 0.04 kPa), NCO content 15.8% by mass, viscosity (25 ° C.) 330 mPa · s, free HDI content 0.3 Mass% modified polyisocyanate S-1 was obtained.

[Example 2] Synthesis of modified polyisocyanate S-2 Modified polyisocyanate S-2 was obtained in the same manner as in Example 1 except that the reaction was performed up to the stopped NCO content shown in Table 1.

[Comparative Example 1] Synthesis of Modified Polyisocyanate H-1 Modified polyisocyanate H-1 was obtained in the same manner as in Example 1 except that the reaction was performed up to the stopped NCO content shown in Table 1.

[Comparative Example 2] Synthesis of modified polyisocyanurate H-2 910 g of HDI and 90 g of 2-ethylhexanol were added to a one-liter four-necked flask equipped with a stirrer, a thermometer, a cooler, and a nitrogen gas introduction tube. They were charged and heated to 85 ° C. with stirring to carry out a urethanization reaction for 2 hours.
Thereafter, 0.25 g of tin octylate (manufactured by Nippon Chemical Industry Co., Ltd.), which is an isocyanurate-forming catalyst, was added to the reaction solution and reacted at 110 ° C., and the reaction was stopped when a predetermined NCO content was reached. 0.6 g of acidic phosphate ester (JP-508, manufactured by Johoku Chemical Industry Co., Ltd.) as an agent was added, and a stop reaction was performed at 50 ° C. for 1 hour.
Excess HDI was removed from this reaction product by thin film distillation (conditions: 140 ° C., 0.04 kPa), NCO content 17.6% by mass, viscosity (25 ° C.) 360 mPa · s, free HDI content 0.3 A mass% modified polyisocyanate H-2 was obtained.

[Comparative Example 3] Synthesis of modified polyisocyanurate H-3 880 g of HDI and 120 g of tridecanol were charged into a one-liter four-necked flask equipped with a stirrer, a thermometer, a cooler, and a nitrogen gas introduction tube. The mixture was heated to 85 ° C. with stirring to conduct a urethanization reaction for 2 hours.
Thereafter, 0.15 g of zirconium octylate (Daiichi Rare Element Chemical Co., Ltd.), which is an allophanatization catalyst, was added to the reaction solution and reacted at 110 ° C., and when a predetermined NCO content was reached. 0.2 g of acidic phosphate ester (JP-508, manufactured by Johoku Chemical Industry Co., Ltd.) which is a reaction terminator was added, and a termination reaction was performed at 50 ° C. for 1 hour.
Excess HDI was removed from this reaction product by thin film distillation (conditions: 140 ° C., 0.04 kPa), NCO content 14.8% by mass, viscosity (25 ° C.) 130 mPa · s, free HDI content 0.3 Mass% modified polyisocyanate H-3 was obtained.

[Comparative Example 4] Synthesis of modified polyisocyanurate H-4 910 g of HDI and 90 g of 2-ethylhexanol were added to a one-liter four-necked flask equipped with a stirrer, a thermometer, a cooler, and a nitrogen gas inlet tube. They were charged and heated to 85 ° C. with stirring to carry out a urethanization reaction for 2 hours.
Thereafter, 0.15 g of zirconium octylate (Daiichi Rare Element Chemical Co., Ltd.), which is an allophanatization catalyst, was added to the reaction solution and reacted at 110 ° C., and when a predetermined NCO content was reached. 0.2 g of acidic phosphate ester (JP-508, manufactured by Johoku Chemical Industry Co., Ltd.) which is a reaction terminator was added, and a termination reaction was performed at 50 ° C. for 1 hour.
Excess HDI was removed from this reaction product by thin film distillation (conditions: 140 ° C., 0.04 kPa), NCO content 16.7% by mass, viscosity (25 ° C.) 130 mPa · s, free HDI content 0.3 Mass% modified polyisocyanate H-4 was obtained.

[Example 3] Synthesis of modified polyisocyanate S-3 In a four-necked flask having a volume of 0.5 liter equipped with a stirrer, a thermometer, a cooler, and a nitrogen gas introduction tube, the modification obtained in Example 1 was performed. 15 g of polyisocyanate S-1 and 85 g of modified polyisocyanate H-3 obtained in Comparative Example 3 were charged and mixed with stirring for 1 hour. The NCO content was 15.0% by mass, the viscosity (25 ° C.) was 160 mPa · s, free A modified polyisocyanate S-3 having an HDI content of 0.2% by mass was obtained.

[Example 4] Synthesis of modified polyisocyanate S-4 Modified polyisocyanate S-4 was obtained in the same manner as in Example 3 except that the amount was changed to the amount shown in Table 1.

About the modified polyisocyanates S-1 to S-4 and H-1 to H-4 obtained in Examples 1 to 4 and Comparative Examples 1 to 4, (formation) of allophanate group, isocyanurate group and urethane group, respectively. The molar ratio was measured. The results are shown in Table 1.
[Measurement method]
^{Using 1} H-NMR (ECX400M, manufactured by JEOL Ltd.), adjacent to the hydrogen atom signal bonded to the nitrogen atom of the allophanate group near 8.5 ppm and the nitrogen atom of the isocyanurate group near 3.7 ppm The area ratio between the hydrogen atom signal of the methylene group and the hydrogen atom signal bonded to the nitrogen atom of the urethane group near 7.0 ppm was obtained. Specific measurement conditions are as follows.
Measurement temperature: 23 ° C
Sample concentration: 0.02 g / 1 ml
Integration count: 32 times Relaxation time: 5 seconds
Solvent: Deuterium dimethyl sulfoxide Chemical shift criteria: Signal of hydrogen atom of methyl group in deuterium dimethyl sulfoxide (2.5 ppm)

In addition, with respect to the modified polyisocyanates S-1 to S-4 and H-1 to H-4 obtained in Examples 1 to 4 and Comparative Examples 1 to 4, 20 to IP solvent 1620 (manufactured by Idemitsu Kosan Co., Ltd.). The solubility at 0 ° C. was measured by the following method. The results are shown in Table 1.
[Measurement method]
1 g of the modified polyisocyanate was weighed out, and IP solvent 1620 was added thereto. The turbid portion was taken as the end point, and the amount (g) of IP solvent 1620 added at that time was determined.
The tolerance was calculated from the following equation using this added amount.
Tolerance = Required amount of organic solvent (g) / Sample amount (1 g)

  As shown in Table 1, it can be seen that the modified polyisocyanates obtained in Examples 1 to 4 have good solubility in IP solvent 1620 having an aniline point of 81 ° C.

[2] Coating Film Test [Examples 5 to 8, Comparative Examples 5 and 6]
After the modified polyisocyanates S-1 to S-4 and H-3, H-4 obtained in Examples 1 to 4 and Comparative Examples 3 and 4 were diluted with the amount of IP solvent 1620 shown in Table 2, A two-component curable coating composition was prepared by blending the acrylic polyol R-1 obtained in Synthesis Example 1 with the ratio shown in Table 2.

The two-component paint compositions prepared in Examples 5 to 8 and Comparative Examples 5 and 6 were each applied to a glass plate with a wet film thickness of 100 μm using an applicator, in an environment with a temperature of 20 ° C. and a relative humidity of 65%. After curing for 7 days, the film was forcibly cured at 100 ° C. for 7 hours to form a coating film having a dry film thickness of 40 to 50 μm. The solvent resistance of the obtained coating film was measured and evaluated by the following method. The results are shown in Table 3.
Note that the modified polyisocyanates H-1 and H-2 obtained in Comparative Examples 1 and 2 were not dissolved in the IP solvent 1620, so the coating test was not performed.

(1) Solvent resistance Mineral Spirit A (manufactured by Shin Nippon Oil Co., Ltd.) was dropped onto the surface of the coating film, wiped with gauze after 1 minute, the dissolved state of the coating film was confirmed, and evaluated according to the following criteria.
○: Not dissolved (appearance hardly changes before dripping)
Δ: slightly dissolved (coating surface becomes rough and white)
X: The coating film dissolves (the glass surface is exposed)

As shown in Table 3, the curing agent contained in the coating compositions of Examples 5 to 8 has good solubility in IP solvent 1620, but the obtained coating film has excellent solvent resistance. I understand.
On the other hand, it turns out that the coating film obtained from the coating composition of Comparative Examples 5 and 6 is inferior in solvent resistance.

Claims (4)

Comprising a polyisocyanate (A) and an organic solvent (B) having an aniline point of more than 70 ° C.,
The polyisocyanate (A) includes a product in which an aliphatic diisocyanate and an alkyl monool having 11 or more carbon atoms are reacted in the presence of tin octylate to form allophanate groups and isocyanurate groups substantially simultaneously. An allophanate group and an isocyanurate group are contained in an allophanate group / isocyanurate group = 95/5 to 65/35 (molar ratio). The curing agent composition for a two-component curable coating material according to claim 1, wherein the allophanate group and the isocyanurate group are contained in an allophanate group / isocyanurate group = 95/5 to 68/32 (molar ratio) .   The curing agent composition for a two-component curable coating composition according to claim 1 or 2, wherein the alkyl monool is an alkyl monool having 11 to 20 carbon atoms.   The said aliphatic diisocyanate is hexamethylene diisocyanate, The hardening | curing agent composition for two-component curable coating materials of any one of Claims 1-3.