JP5445451B2 - Polyisocyanate composition and two-component coating composition using the same - Google Patents

Description

  The present invention relates to a polyisocyanate composition and a two-component coating composition using the same.

Two-component urethane-based paints 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, and automobiles 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 from the viewpoint of improving the working environment and reducing the burden on the global environment. In addition, when repairing or repainting by repainting the old paint film, if the repair paint contains a strong solvent with high dissolving power, the old paint film will swell or dissolve, It may be necessary to repair the membrane. 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, Patent Document 1 (Japanese Patent Application Laid-Open No. 8-198928) discloses a polyol having an alicyclic diisocyanate and a dilutability with a low polar organic solvent of 100% or more as a polyisocyanate excellent in dilutability with a low polar solvent. Polyisocyanates obtained by reacting with are disclosed.

  Patent Document 2 (Japanese Patent Laid-Open No. 2008-24828) discloses aliphatic and / or alicyclic diisocyanates and carbon as polyisocyanates having excellent solubility in low-polar organic solvents and compatibility with silicate compounds. Polyisocyanate compounds obtained from several 1 to 20 monoalcohols and having a predetermined allophanate group / isocyanurate group molar ratio and a predetermined molecular weight distribution are disclosed.

  Although the polyisocyanates of Patent Document 1 and Patent Document 2 are all excellent in solubility in low-polar organic solvents, various properties such as compatibility with the main component polyol compound and surface hardness of the resulting coating film are obtained. There is room for further improvement in terms of physical properties. There is also room for improvement in the selection of low polarity solvents.

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

  The present invention has been made in view of the above circumstances, and provides a coating film that is soluble in a low-polar organic solvent, excellent in compatibility with a polyol compound, and excellent in various physical properties such as surface hardness. It is an object of the present invention to provide a polyisocyanate composition to be obtained and a two-component coating composition using the same.

  As a result of intensive studies in order to achieve the above object, the present inventor has obtained an allophanate group / isocyanurate group of a polyisocyanate obtained by reacting hexamethylene diisocyanate with an aliphatic monoalcohol having 11 to 20 carbon atoms. By making the molar ratio within a predetermined range, solubility in low-polar organic solvents is improved, and various physical properties such as surface hardness are improved in coatings obtained from paints containing this polyisocyanate and polyol. The present invention has been completed.

That is, the present invention
1. A polyisocyanate obtained by reacting hexamethylene diisocyanate with an aliphatic monoalcohol having 11 to 20 carbon atoms, and a low polar organic solvent having an aniline point of 10 to 70 ° C or a low polar organic having a mixed aniline point of 5 to 50 ° C A solvent, and the polyisocyanate has an allophanate group, an isocyanurate group and a urethane group in the molecule, and the molar ratio of the allophanate group to the isocyanurate group is allophanate group / isocyanurate group = 70 / 30-30. / 70, a polyisocyanate composition,
2. The polyisocyanate composition according to 1, wherein the reaction is performed simultaneously with an allophanate reaction and an isocyanurate reaction;
3. 2 polyisocyanate composition wherein the catalyst for the allophanatization reaction and isocyanurate reaction is tin octylate;
4). Hexamethylene diisocyanate and an aliphatic monoalcohol having 11 to 20 carbon atoms are allophanated and isocyanurated in the presence of a tin octylate catalyst, and the molar ratio of allophanate group to isocyanurate group is allophanate group / method for producing a polyisocyanate, characterized in Rukoto give polyisocyanate isocyanurate group = 70 / 30-30 / 70,
5. A two-component coating composition containing any one of the polyisocyanate compositions 1 to 3 and a polyol compound is provided.

The polyisocyanate contained in the composition of the present invention is excellent in solubility in a low-polar organic solvent (weak solvent) and has good compatibility with a fluorine-based or acrylic polyol used in a two-component paint.
Since this polyisocyanate has a high isocyanurate content, various coating film properties such as surface hardness can be improved by using this polyisocyanate as a curing agent for a two-component coating composition.
In addition, since the two-component coating composition of the present invention is soluble in a low-polar organic solvent (weak solvent), it does not erode the base layer during overcoating, and thus has excellent recoatability. Yes.

Hereinafter, the present invention will be described in more detail.
The polyisocyanate composition according to the present invention includes a polyisocyanate obtained by reacting hexamethylene diisocyanate with an aliphatic monoalcohol having 11 to 20 carbon atoms, a low polarity organic solvent having an aniline point of 10 to 70 ° C., or a mixture The polyisocyanate has an allophanate group, an isocyanurate group and a urethane group in the molecule, and the molar ratio of these allophanate groups and isocyanurate groups is an allophanate group. / Isocyanurate group = 70 / 30-30 / 70 is satisfied.

In the present invention, when the allophanate group / isocyanurate group (molar ratio) is out of the above range, the solubility of the resulting polyisocyanate in the low-polar organic solvent is lowered, and the coating film obtained using this composition Physical properties are reduced.
More preferably, it is allophanate group / isocyanurate group (molar ratio) = 60 / 40-30 / 70, and still more preferably 40 / 60-30 / 70.
Further, the content of the urethane group is not particularly limited, but in the polyisocyanate of the present invention, 0.1 to 2 mol% is preferable with respect to the total molar amount of allophanate group and isocyanurate group. 0.5 to 2 mol% is more preferable.
The molar ratio of each functional group can be calculated by ¹ H-NMR measurement.

Examples of the aliphatic monoalcohol having 11 to 20 carbon atoms to be reacted with hexamethylene diisocyanate include, for example, 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. These may be used alone or in combination of two or more.
Among these alcohols, 1-tridecanol, isotridecanol, 1-dodecanol, 1-eicosanol, 1-heptadecanol are considered in consideration of further increasing the solubility of the resulting polyisocyanate composition in a low-polar organic solvent. 1-nonadecanol, 1-tetradecanol, 1-pentadecanol, stearyl alcohol, isostearyl alcohol and 2-octyldodecanol are preferable, and 1-tridecanol, isotridecanol and 2-octyldodecanol are more preferable.

The reaction of hexamethylene diisocyanate and monoalcohol can be carried out by heating 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, but in the present invention, it is preferably performed 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 used, for example, a metal salt of a carboxylic acid. 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, glutaconic 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.

The metal constituting the metal salt of carboxylic acid includes alkali metals such as lithium, sodium and potassium; alkaline earth metals such as magnesium, calcium and barium; other typical metals such as tin and lead; manganese, iron, Examples include transition metals such as cobalt, nickel, copper, zinc, and zirconium.
These carboxylic acid metal salts can be used alone or in combination of two or more. 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, such as a polar aprotic solvent 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 the reaction is stopped, 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 as a polyisocyanate composition (when it satisfies the above-mentioned allophanate group / isocyanurate group range).

The allophanate-modified polyisocyanate obtained as described above mainly has allophanate groups, but side reactions occur due to reactions under conditions where isocyanate groups are present in excess, and isocyanurate groups are generated. To do.
Therefore, the molar ratio of allophanate groups and isocyanurate groups in the resulting polyisocyanate is adjusted to about 70/30 to 30/70 by appropriately adjusting various conditions such as the ratio of [NCO] / [OH] in allophanatization. It can adjust suitably in the range.

In addition, the polyisocyanate allophanated by the above method can be further isocyanurated to adjust the allophanate group / isocyanurate group molar ratio.
Examples of the isocyanuration reaction include a method in which polyisocyanate is modified (trimerized) 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 them, metal salts of aliphatic carboxylic acids are preferable, and for example, sodium salts, potassium salts, and tin salts of carboxylic acids such as acetic acid, propionic acid, undecyl acid, capric acid, octylic acid, and myristic acid are preferable. In addition, as commercially available products, 2-hydroxypropyltrimethylammonium octylate (DABCO TMR, manufactured by Air Products Japan), potassium octylate (DABCO K-15, manufactured by Air Products Japan) may be used. it can.

As described above, the polyisocyanate of the present invention can be produced by a technique in which allophanatization and isocyanuration are performed simultaneously, or a technique in which allophanation and isocyanuration are performed in stages, The method of simultaneously performing the allophanatization reaction and the isocyanurate reaction is optimal.
At this time, as the catalyst, it is preferable to use tin octylate among the above-mentioned various catalysts from the viewpoint of easy reaction control.
Further, two or more polyisocyanates can be used as a mixture. In this case, the polyisocyanate satisfies the molar ratio of the allophanate group and the isocyanurate group as long as the mixture satisfies the molar ratio of the allophanate group and isocyanurate group described above. Some non-polyisocyanates can also be used.

  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 from the viewpoint of handling.

Since the coating composition of the present invention is characterized by the above-described polyisocyanate, the other component to be reacted and cured may be appropriately selected from polyol compounds generally used for the application.
Specific examples include acrylic polyols and fluorine polyols. Among these, 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.
In the present invention, a polyol compound that is soluble in a low-polar organic solvent is also preferred because of the property of the polyisocyanate that the solubility in a low-polar organic solvent is good.

  The acrylic polyol soluble in the low-polar organic solvent is not particularly limited, and a known weak solvent-soluble acrylic polyol can be used. Specific examples thereof include commercially available products such as ACRICID HU-596 (Dainippon Ink Chemical Co., Ltd.), Excelol 410 (Asia Kogyo Co., Ltd.), and Hitaroid 6500 (Hitachi Chemical Industry Co., Ltd.). ) And the like.

  It does not specifically limit as a fluorine-type polyol soluble in a low polar organic solvent, A well-known weak solvent soluble type 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 mgKOH / g, the coating film is not sufficiently crosslinked, and the physical properties such as the coating film strength tend to decrease. When the hydroxyl value exceeds 300 mgKOH / g, the crosslinking density of the coating film becomes too high and becomes hard. In some cases, followability and flexibility with respect to the substrate may be reduced.
The number average molecular weight of the polyol compound is preferably from 5,000 to 20,000, more preferably from 7,000 to 15,000, considering the strength of the resulting coating film and the handleability of the paint. The number average molecular weight is a measured value (polystyrene equivalent value) by gel permeation chromatography (GPC) measurement by differential refractometer detection.

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

The polyisocyanate composition used in the coating composition of the present invention contains a low polarity organic solvent having an aniline point of 10 to 70 ° C or a low polarity organic solvent having a mixed aniline point of 5 to 50 ° C. These low polar organic solvents may be added in advance to the polyisocyanate, or may be added to the polyisocyanate for the purpose of adjusting the viscosity before mixing the polyisocyanate and the polyol.
Moreover, a low polar organic solvent may be added at the time of preparation of a polyol composition as needed, and may be further added at the time of mixing a polyisocyanate composition and a polyol.

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 “mixed aniline point” is the lowest temperature at which 2 volumes of aniline, 1 volume of sample, and 1 volume of 1-heptane exist as a uniform mixed solution. The aniline point and mixed aniline point can be measured according to the aniline point and mixed aniline point test method described in JIS K 2256.
Since aniline has a freezing point of −6 ° C., the aniline point cannot be measured at temperatures below that. Therefore, a mixed aniline point is used in order to measure the solubility of the organic solvent over a wider area by mixing aniline with heptane.

  The aniline point is preferably 10 to 70 ° C, more preferably 10 to 60 ° C, and more preferably 10 to 50 ° C. Moreover, in the case of a mixed aniline point, 5-50 degreeC is preferable. If the aniline point is less than 10 ° C. or the mixed aniline point is less than 5 ° C., the base is likely to be eroded, and if the aniline point exceeds 70 ° C. or the mixed aniline point exceeds 50 ° C., it becomes difficult to dissolve the polyisocyanate of the present invention.

  Examples of such organic solvents include methylcyclohexane (aniline point: 40 ° C.), ethylcyclohexane (aniline point: 44 ° C.), mineral spirit (aniline point: 56 ° C.), and turpentine oil (aniline point: 44 ° C.). Moreover, under the trade name marketed as petroleum hydrocarbon, High Aromatic White Spirit (HAWS) (manufactured by Shell Chemicals Japan, aniline point: 17 ° C.), Low Aromatic White Spirit (LAWS) (manufactured by Shell Chemicals Japan, Aniline point: 44 ° C.), Essonaphtha No. 6 (ExxonMobil, aniline point: 43 ° C), Pegazole 3040 (ExxonMobil, aniline point: 55 ° C), A Solvent (manufactured by Nippon Oil Corporation, aniline point: 45 ° C), Clensol (Nippon Oil) Manufactured by the company, aniline point: 64 ° C.), mineral spirit A (manufactured by Nippon Oil Corporation, aniline point: 43 ° C.), Hyalom 2S (manufactured by Nippon Oil Corporation, aniline point: 44 ° C.), Solvesso 100 (manufactured by ExxonMobil Corporation) , Mixed aniline point: 14 ° C.), Solvesso 150 (manufactured by ExxonMobil, mixed aniline point: 18.3 ° C.), Swazol 100 (manufactured by Maruzen Petrochemical Co., Ltd., mixed aniline point: 24.6 ° C.), swazole 200 (Maruzen) Petrochemical Co., Ltd., mixed aniline point: 23.8 ° C), Swazol 1000 (Maruzen Petrochemical Co., Ltd., mixed aniline point: 12.7 ° C), Zol 1500 (Maruzen Petrochemical Co., Ltd., mixed aniline point: 16.5 ° C), Swazol 1800 (Maruzen Petrochemical Co., Ltd., mixed aniline point: 15.7 ° C), Idemitsu Ipsol 100 (Idemitsu Kosan Co., Ltd., mixed aniline point) : 13.5 ° C), Idemitsu Ipsol 150 (Idemitsu Kosan Co., Ltd., mixed aniline point: 15.2 ° C), Pegasol ARO-80 (ExxonMobil Corp., mixed aniline point: 25 ° C), Pegazole R-100 (Exxon) Mobil Corp., mixed aniline point: 14 ° C), Akiraishi Special Hyzol (manufactured by Shell Chemicals Japan, mixed aniline point: 12.6 ° C), Nisseki Hysol (manufactured by Nippon Oil Corporation, mixed aniline point: 17 ° C or less) ) And the like. These organic solvents can be used individually by 1 type or in mixture of 2 or more types.

An organic solvent having an aniline point of 10 ° C. or higher or a mixed aniline point of 5 ° C. or higher is characterized by low odor. Therefore, the coating composition of the present invention containing such a low polarity organic solvent is excellent from the viewpoint of environmental resistance.
Moreover, since the low polar organic solvent as described above has a low dissolving power and does not easily attack the base, the coating composition can be repeatedly applied and is also useful as a repair coating.

  In addition, the said coating composition may contain 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 a coating film is produced from the coating composition of the present invention, brushing, roller coating, spraying 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 dip 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 substrate, or may be applied from above the sealing, 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 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, the viscosity is a value measured with a B-type rotational viscometer.

[1] Production of polyisocyanate [Example 1]
Into a 1 liter four-necked flask equipped with a stirrer, thermometer, cooling pipe, and nitrogen gas introduction pipe, hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., NCO content: 49.9% by mass, hereinafter referred to as HDI) ) 880 g and tridecanol (manufactured by Kyowa Hakko Kogyo Co., Ltd.) 120 g were charged, and these were heated to 85 ° C. with stirring, and subjected to a urethanization reaction for 3 hours.
Thereafter, 0.1 g of tin octylate (manufactured by Nippon Chemical Industry Co., Ltd.), which is an allophanate and isocyanurate catalyst, was added to the reaction solution and reacted at 110 ° C. until a predetermined NCO content was reached. Then, 0.4 g of acidic phosphate ester (JP-508, manufactured by Johoku Chemical Industry Co., Ltd.) as a reaction terminator was added, and a termination reaction was performed at 50 ° C. for 1 hour.
Excess HDI was removed from the reaction product by thin-film distillation (conditions: 140 ° C., 0.04 kPa), NCO content 15.8% by mass, viscosity (25 ° C.) 320 mPa · s, free HDI content 0.1 Mass% modified polyisocyanate S-1 was obtained.

[Examples 2 to 4]
Modified polyisocyanates S-2 to S-4 were obtained in the same procedure as in Example 1 except that the amount of the catalyst and the like and the NCO content were changed as shown in Table 1.

[Example 5]
In a 1-liter four-necked flask equipped with a stirrer, a thermometer, a condenser tube, and a nitrogen gas inlet tube, 850 g of HDI (manufactured by Nippon Polyurethane Industry Co., Ltd., NCO content: 49.9% by mass) and Calcoal 200GD 150 g (2-octyldodecanol, manufactured by Kao Co., Ltd.) was charged, and these were heated to 85 ° C. with stirring, and urethanized for 3 hours.
Thereafter, 0.2 g of tin octylate (manufactured by Nippon Chemical Industry Co., Ltd.), which is an allophanate and isocyanurate catalyst, was added to the reaction solution and reacted at 110 ° C. until a predetermined NCO content was reached. Then, 0.8 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 15.7% by mass, viscosity (25 ° C.) 560 mPa · s, free HDI content 0.2 Mass% modified polyisocyanate S-5 was obtained.

[Example 6]
Modified polyisocyanate S-6 was obtained in the same procedure as in Example 5 except that the amount of the catalyst and the like and the NCO content were changed as shown in Table 1.

[Comparative Example 1]
Into a 1 liter four-necked flask equipped with a stirrer, a thermometer, a condenser tube, and a nitrogen gas introduction tube, 850 g of HDI and 150 g of Calcoal 200GD (2-octyldodecanol, manufactured by Kao Corporation) were charged. While stirring, the mixture was heated to 85 ° C. and subjected to urethanization reaction for 3 hours.
Thereafter, 0.4 g of tin octylate (manufactured by Nippon Chemical Industry Co., Ltd.), which is an allophanatization and isocyanuration catalyst, is added to the reaction solution, and a predetermined NCO content is reached at 110 ° C. Then, 2.0 g of acidic phosphate ester (JP-508, manufactured by Johoku Chemical Industry Co., Ltd.), which is a reaction terminator, was added, and the reaction was terminated 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 15.3% by mass, viscosity (25 ° C.) 2,500 mPa · s, free HDI content 0 1% by mass of modified polyisocyanate H-1 was obtained.

[Comparative Example 2]
HDI880g and tridecanol (manufactured by Kyowa Hakko Kogyo Co., Ltd.) 120g were charged into a 1 liter four-necked flask equipped with a stirrer, a thermometer, a cooling pipe, and a nitrogen gas introduction pipe. Heated and urethanized for 3 hours.
Then, 0.1 g of zirconium octylate (Daiichi Rare Element Chemical Co., Ltd.), which is an allophanate catalyst, was added to the reaction solution and reacted at 110 ° C. until 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 0.1 A mass% modified polyisocyanate H-2 was obtained.

[Comparative Example 3]
A 4-liter flask with a capacity of 1 liter equipped with a stirrer, thermometer, cooling pipe, and nitrogen gas introduction pipe was charged with 910 g of HDI and 90 g of 2-ethylhexanol, and immediately heated to 80 ° C. to conduct a urethanization reaction for 2 hours. It was.
Thereafter, 0.1 g of 2-hydroxypropyltrimethylammonium octylate (DABCO TMR, manufactured by Air Products Japan), which is an isocyanuration catalyst, is added and reacted at 80 ° C. until a predetermined NCO content is reached. Then, 0.8 g of acidic phosphate ester (JP-508, manufactured by Johoku Chemical Industry Co., Ltd.) as 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: 130 ° C., 0.04 kPa), NCO content 19.1% by mass, viscosity (25 ° C.) 700 mPa · s, free HDI content 0.2 Mass% modified polyisocyanate H-3 was obtained.

[Example 7]
In a 1-liter four-necked flask equipped with a stirrer, a thermometer, a cooling pipe, and a nitrogen gas introduction pipe, 130 g of the polyisocyanate S-4 obtained in Example 4 and the polyisocyanate obtained in Comparative Example 2 were used. 70 g of isocyanate H-2 is charged and stirred and mixed for 1 hour to obtain a modified polyisocyanate S-7 having an NCO content of 16.0% by mass, a viscosity (25 ° C.) of 240 mPa · s, and a free HDI content of 0.2% by mass. It was.

[Comparative Example 4]
In a 1-liter four-necked flask equipped with a stirrer, a thermometer, a cooling tube, and a nitrogen gas introduction tube, 100 g of polyisocyanate S-4 obtained in Example 4 and the polyisocyanate obtained in Comparative Example 2 were used. 100 g of isocyanate H-2 is charged and stirred and mixed for 1 hour to obtain a modified polyisocyanate H-4 having an NCO content of 15.8% by mass, a viscosity (25 ° C.) of 210 mPa · s, and a free HDI content of 0.2% by mass. It was.

About each polyisocyanate obtained in the said Examples 1-7 and Comparative Examples 1-4, the (formation) molar ratio of an allophanate group, an isocyanurate group, and a urethane group was measured with the following method, respectively. The results are shown in Table 1.
[Measurement method]
^{Using 1} H-NMR (Gemini 2000 (300 MHz) manufactured by Varian), the signal of the hydrogen atom bonded to the nitrogen atom of the allophanate group near 8.5 ppm and the methylene adjacent to the nitrogen atom of the isocyanurate group near 3.7 ppm It was determined from the area ratio between the signal of the hydrogen atom of the group and the signal of the hydrogen atom bonded to the nitrogen atom of the urethane group near 7.0 ppm. Specific measurement conditions are as follows.
Measurement temperature: 23 ° C
Sample concentration: 0.1 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)

Moreover, about each polyisocyanate obtained in Examples 1-7 and Comparative Examples 1-4, the solubility in 20 degreeC with respect to mineral spirit A (made by Nippon Oil Corporation) was measured with the following method. The results are also shown in Table 1.
[Measurement method]
1 g of polyisocyanate was weighed out, and mineral spirit A was added thereto. The turbid portion was taken as the end point, and the amount (g) of mineral spirit A added at that time was determined.
Using this added amount, tolerance was calculated from the following formula (1).
Tolerance = Required amount of organic solvent (g) / Sample amount (1 g) (1)

[2] Production of two-component coating composition [Examples 8 to 14, Comparative Examples 5 to 8]
Each polyisocyanate and mineral spirit A (manufactured by Shin Nippon Oil Co., Ltd.) (polyisocyanate composition) obtained in Examples 1 to 7 and Comparative Examples 1 to 4 and acrylic polyol (Acridic HU-596, large Nippon Ink Chemical Co., Ltd.), titanium oxide (CR-90, Ishihara Sangyo Co., Ltd.), and mineral spirit A (Shin Nippon Oil Co., Ltd.) are blended in the proportions shown in Table 2. A two-component coating composition was prepared.

Steel plates obtained by degreasing the two-component paint compositions prepared in Examples 8 to 14 and Comparative Examples 6 and 8 with methyl ethyl ketone (JIS G3141 trade names: SPCC-SB, PF-1077 treatment, Nippon Test Panel Industry Co., Ltd.) The product was applied with a wet film thickness of 100 μm and cured for 7 days in an environment of a temperature of 20 ° C. and a relative humidity of 65% to form a coating film having a dry film thickness of 40 to 50 μm. About the obtained coating film, the following each characteristic was evaluated. The results are shown in Table 3.
Note that the two-component coating compositions prepared in Comparative Examples 5 and 7 were not tested because of insufficient tolerance to low-polar solvents.

(1) Bending resistance Using a cylindrical mandrel with a diameter of 2 mm, the coating film cracked when it was bent by a cylindrical mandrel and the presence or absence of peeling from the steel plate, JIS K-5600-5-1: 1999 Evaluation was performed according to a flex resistance test. Those in which no cracking or peeling of the coating film occurred were regarded as acceptable.
(2) Cupping resistance JIS K-5600-5-2: 1999 cupping resistance test using an indenter to check for cracks in the coating film when it was partially deformed by indentation, and whether or not it peeled off from the steel sheet. Evaluated in accordance with. The indentation depth (mm) at which the coating film was cracked or peeled off by the indenter was defined as cupping resistance.
(3) Weight drop resistance Using a weight of 10.3 mm in diameter and a weight of 0.5 kg, JIS K-5600 is used to determine whether the coating film is cracked or peeled off from the steel sheet when subjected to deformation due to weight drop. -5-3: Evaluated according to 1999 weight drop test. The minimum drop height (cm) at which the coating film cracked and peeled was defined as the weight drop resistance.
(4) Coating film hardness The hardness of the coating film surface was measured based on the scratch hardness test (pencil method) of JIS K-5600-5-4: 1999. The hardness of the hardest pencil with no scratch marks on the surface of the coating film was defined as the coating film hardness.
(5) Adhesiveness The adhesiveness of the coating film is determined from the substrate when a cross-cut tape peeling test based on JIS K-5600-5-6: 1999, a right-angle lattice pattern is cut into the coating film and penetrates to the substrate. The coating film was evaluated for resistance to peeling (cross-cut method).

  As shown in Table 3, it can be seen that the coating films obtained from the coating compositions of Examples 8 to 14 are excellent in hardness and other characteristics.

Claims (5)

A polyisocyanate obtained by reacting hexamethylene diisocyanate with an aliphatic monoalcohol having 11 to 20 carbon atoms, and a low polar organic solvent having an aniline point of 10 to 70 ° C or a low polar organic having a mixed aniline point of 5 to 50 ° C Containing solvent,
The polyisocyanate has an allophanate group, an isocyanurate group and a urethane group in the molecule,
The polyisocyanate composition, wherein the allophanate group and isocyanurate group have a molar ratio of allophanate group / isocyanurate group = 70/30 to 30/70.   The polyisocyanate composition according to claim 1, wherein the reaction simultaneously performs an allophanate reaction and an isocyanurate reaction.   The polyisocyanate composition according to claim 2, wherein the catalyst for the allophanatization reaction and isocyanurate reaction is tin octylate. Hexamethylene diisocyanate and an aliphatic monoalcohol having 11 to 20 carbon atoms are allophanated and isocyanurated in the presence of a tin octylate catalyst, and the molar ratio of allophanate group to isocyanurate group is allophanate group / method for producing a polyisocyanate, characterized in Rukoto give polyisocyanate isocyanurate group = 70 / 30-30 / 70.   A two-component coating composition comprising the polyisocyanate composition according to any one of claims 1 to 3 and a polyol compound.