TWI481633B - Polyisocyanate composition and two-pack coating composition using the same - Google Patents

Description

Polyisocyanate composition and two-component paint composition using the same

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

The two-liquid type urethane-based coating which is used as a component of polyisocyanate is used as a coating film having good weather resistance and abrasion resistance, and is used in buildings, civil structures, and the like in the prior art. Coating of outdoor substrates, repair of automobiles, painting of plastics, etc.

In the coating material, a strong solvent such as an aromatic hydrocarbon solvent such as toluene or xylene or an ester solvent such as butyl acetate is used as the height of the polyisocyanate, that is, a solvent having a strong dissolving power is used.

Since these strong solvents are strong in odor, they improve the surface of the working environment and reduce the global environmental load. In recent years, there has been a tendency to avoid them. Further, when the old coating film is recoated and repaired, and the coating is renewed, when the strong solvent having a high dissolving power in the coating material for repair is contained, the old coating film is swollen or dissolved, and it is necessary to repair the old coating film. As a result, problems such as enlargement and cumbersome coating work, increase in coating cost, and extension of the construction period have occurred.

In view of the above, in recent years, it has been advocated to develop a polyisocyanate which is easily soluble in a low polar organic solvent.

In the case of a polyisocyanate having a low solubility in a low-polarity solvent, it is disclosed that the dilution of the alicyclic diisocyanate and the low-polarity solvent is 100%, as disclosed in Japanese Laid-Open Patent Publication No. Hei 8-198928. The above polyol is reacted to obtain a polyisocyanate.

Further, in the case of a polyisocyanate having a good solubility in a low-polarity organic solvent and a good solubility of a phthalic acid ester compound, it is disclosed in the patent document 2 (Japanese Unexamined Patent Publication No. Publication No. 2008-24828). A polyisocyanate compound having a specific allophanate group/trimeric isocyanate group molar ratio and a specific molecular weight distribution obtained by a cyclic diisocyanate and a carbon number of 1 to 20 monol.

The polyisocyanate of Patent Document 1 and Patent Document 2 has good solubility in a low-polarity organic solvent, and is compatible with various other physical properties such as the mutual solubility of the polyol compound of the main component and the surface hardness of the obtained coating film. There is room for further improvement, and there is room for improvement in the choice of low-polarity solvents.

Patent Document 1: Special Kaiping No. 8-198928

Patent Document 2: Special Opening 2008-24828

In view of the above problems, the present invention provides a polyisocyanate composition which is soluble in a low-polarity organic solvent and which has good miscibility with a polyol compound, and which can impart various physical properties such as surface hardness, and a liquid solution using the same. The type of coating composition is for its purpose.

In order to achieve the object, the inventors of the present invention have found that the allophanate group/trimeric isocyanate group of the polyisocyanate obtained by reacting hexamethylene diisocyanate with an aliphatic monool having 11 to 20 carbon atoms is obtained. When the Mohr ratio is made to a specific range, the solubility for the low-polarity organic solvent can be improved, and at the same time, the coating film obtained from the coating material containing the polyisocyanate and the polyol can improve various physical properties starting from the surface hardness, thereby completing this invention.

That is, the present invention provides:

1. A polyisocyanate obtained by reacting hexamethylene diisocyanate with an aliphatic monohydric alcohol having 11 to 20 carbon atoms and a low polar organic solvent or mixed aniline having an aniline point of 10 to 70 ° C is 5 to 50 ° C low. a polar organic solvent having an allophanate group, a trimeric isocyanate group, and a urethane group in the molecule, and the molar ratio of the allophanate group to the trimer isocyanate group is urea A polyisocyanate composition characterized by a carbamate group/trimeric isocyanate group = 70/30 to 30/70.

2. This reaction is a polyisocyanate composition of the above-mentioned one which carries out the allophanation reaction and the isocyanation reaction.

3. The catalyst for the allophanation reaction and the trimeric isocyanation reaction is a polyisocyanate composition of 2 parts of tin octylate.

4. A method for producing a polyisocyanate characterized by a uremic acid esterification reaction and a trimerization reaction of a hexamethylene diisocyanate and an aliphatic monoalcohol having 11 to 20 carbon atoms in the presence of a tin octanoate catalyst .

5. A two-component coating composition comprising a polyisocyanate composition of any one of items 1 to 3 and a polyol compound.

The polyisocyanate contained in the composition of the present invention is excellent in solubility in a low-polar organic solvent (weak solvent), and is excellent in miscibility with a fluorine-based or acrylic-based polyol used in a two-component type coating.

Since the polyisocyanate has a high content of the trimeric isocyanate, it can be used as a hardener for the two-liquid type coating composition, and the surface hardness can be improved by the surface hardness.

Further, since the two-liquid type coating composition of the present invention is soluble in a low-polar organic solvent (weak solvent), it does not attack the underlayer at the time of repeated coating, and has good recoatability.

[Best form of implementation of the invention]

Hereinafter, the present invention will be described in more detail.

The polyisocyanate composition of the present invention contains a polyisocyanate obtained by reacting hexamethylene diisocyanate with an aliphatic monohydric alcohol having 11 to 20 carbon atoms, and a low polar organic solvent having an aniline point of 10 to 70 ° C, or a mixed aniline point. a low polar organic solvent of 5 to 50 ° C, the polyisocyanate has an allophanate group, a trimeric isocyanate group and a urethane group in the molecule, and the allophanate group and the trimer isocyanate group The molar ratio is such that the allophanate group/trimeric isocyanate group is 70/30 to 30/70.

In the present invention, when the allophanate group/trimeric isocyanate group (mole ratio) is out of the above range, the solubility of the obtained polyisocyanate to the low polar organic solvent is lowered, and the composition is obtained by using the composition. The physical properties of the coating film are also lowered.

Preferably, the allophanate group/trimeric isocyanate group (mole ratio) = 60/40 to 30/70, more preferably 40/60 to 30/70.

Further, the content of the urethane group is not particularly limited, and in general, the polyisocyanate of the present invention is 0.1 mol% to 2 for the total amount of allophanate groups and trimeric isocyanate groups. Mox% is preferred, and more preferably 0.5 to 2 mol%.

Further, the molar ratio of each of the above functional groups can be calculated by ¹ H-NMR measurement.

As the aliphatic monoalcohol having a carbon number of 11 to 20 reacted as hexamethylene diisocyanate, such as isotridecyl alcohol, 1-undecyl alcohol, 1-dodecyl alcohol, 1-eicosanol, 1-heptadecanol, 1-nonadecanol, 1-tridecyl alcohol, 1-tetradecanol, 1-pentadecanol, stearyl alcohol, isostearyl alcohol, 3-ethyl-4,5,6-trimethyloctanol, 4,5,6,7-tetramethylnonanol, 4,5,8-trimethylnonanol, 4,7,8-trimethylnonanol, 2-hexyldodecanol, 2-octyl ten Examples of the diol, 2-dodecyl decyl alcohol, and 2-hexadecyl octadecyl alcohol. These may be used alone or in combination of two or more.

In these alcohols, the consideration is further improved. After obtaining the solubility of the polyisocyanate composition in the low-polar organic solvent, 1-tridecyl alcohol, isotridecyl alcohol, 1- lauryl alcohol, 1-undecyl alcohol, 1- Preferably, heptyl alcohol, 1-nonanol, 1-tetradecanol, 1-pentadecanol, stearyl alcohol, isostearyl alcohol, 2-octyl lauryl alcohol, more preferably 1-tenth Triol, isotridecyl alcohol, 2-octyl lauryl alcohol.

The reaction of hexamethylene diisocyanate with a monool can be carried out after heating at 50 to 150 ° C in the presence or absence of an organic solvent.

The allophanation can be carried out simultaneously with the urethane, or after the urethanization, and it is preferred in the present invention to be carried out after the urethanization. When the urethanation is carried out simultaneously with the allophanation, the reaction can be carried out in the presence of an allophanate catalyst, and when the allophanation is carried out after the ureidolation, After the ureidolation reaction for a specific period of time in the absence of the allophanate catalyst, the allophanate catalyst may be added to carry out the allophanation reaction.

As the allophanate catalyst, it can be suitably selected from known catalysts, for example, a metal salt of a carboxylic acid. As the carboxylic acid, for example, a saturated aliphatic carboxylic acid such as acetic acid, propionic acid, butyric acid, caproic acid, caprylic acid, lauric acid, myristic acid, palmitic acid, stearic acid or 2-ethylhexanoic acid, or cyclohexanecarboxylic acid can be used. a saturated monocyclic carboxylic acid such as an acid or a cyclopentanecarboxylic acid; a saturated cyclic carboxylic acid such as a bicyclo (4.4.0) decane-2-carboxylic acid; or a carboxylic acid mixture of a naphthenic acid or the like; a monocarboxylic acid such as an unsaturated aliphatic carboxylic acid such as linoleic acid, linolenic acid, soybean oil fatty acid or tall oil fatty acid, an aromatic aliphatic carboxylic acid such as diphenylacetic acid, or an aromatic carboxylic acid such as benzoic acid or toluic acid. Acids; phthalic acid, isophthalic acid, terephthalic acid, naphthalene dicarboxylic acid, succinic acid, tartaric acid, oxalic acid, malonic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, pentane Aenedioic acid, azelaic acid, sebacic acid, 1,4-cyclohexanedicarboxylic acid, α-hydrogenated muconic acid, β-hydrogenated fatty acid, α-butyl-α-ethylglutaric acid, α Examples of polycarboxylic acids such as β-diethyl succinic acid, maleic acid, fumaric acid, trimellitic acid, and pyromellitic acid.

Further, examples of the metal constituting the metal carboxylate include alkali metals such as lithium, sodium, and potassium; alkaline earth metals such as magnesium, calcium, and barium; and other typical metals such as tin and lead; manganese, iron, and cobalt. Examples of transition metals such as nickel, copper, zinc, and zirconium.

These carboxylic acid metal salts may be used singly or in combination of two or more kinds, and the amount of the allophanate catalyst used is preferably 0.0005 to 1% by mass based on the total mass of the polyisocyanate and the alcohol. The preferred one is 0.001 to 0.1% by mass.

When the reaction is carried out in the presence of an organic solvent, various organic solvents which do not affect the reaction can be used, and specific examples thereof include aliphatic hydrocarbons such as n-hexane and octane; cyclohexane and methylcyclohexane; Alicyclic hydrocarbons; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone; esters of methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, etc.; Glycol ether esters such as diol ether acetate, propylene glycol methyl ether acetate, 3-methyl-3-methoxybutyl acetate, ethyl-3-ethoxypropionate; An ether such as diethyl ether, tetrahydrofuran or dioxane; a halogenated hydrocarbon such as methyl chloride, dichloromethane, chloroform, carbon tetrachloride, methyl bromide, diiodomethane or dichloroethane; N-methyl Examples of polar aprotic solvents such as pyrrolidone, dimethylformamide, dimethylacetamide, dimethyl hydrazine, and hexamine hexamethylphosphonate. These solvents may be used alone or in combination of two or more.

After completion of the reaction, a reaction stopper such as phosphoric acid or phosphate is added to the reaction system, and the reaction is stopped at 30 to 100 ° C for 1 to 2 hours to stop the allophanation reaction.

After the reaction is stopped, the unreacted component is removed by a known method such as thin film distillation to obtain an allophanate-modified polyisocyanate.

The obtained allophanate-modified polyisocyanate (when the above-mentioned range of the allophanate group/trimeric isocyanate group is satisfied) can be directly used as a polyisocyanate composition.

Further, the allophanate-modified polyisocyanate obtained as described above has an allophanate group, and a side reaction occurs via a reaction or the like under the condition that an isocyanate group is excessively present. A trimeric isocyanate is formed.

Therefore, after adjusting various conditions such as the ratio of [NCO]/[OH] in the allophanation, the molar ratio of the allophanate group to the trimeric isocyanate group in the obtained polyisocyanate can be appropriately adjusted. In the range of 70/30 to 30/70.

Further, according to the above method, the allophanate-forming polyisocyanate is further subjected to trimerization, and the allyl group of the allophanate group/trimeric isocyanate group can also be adjusted.

As a trimerization reaction, for example, a method of modifying (trimerization) a polyisocyanate in the presence of a trimeric isocyanate catalyst. As the method of the modification, a method as disclosed in Japanese Patent No. 3371480 and JP-A-2002-241458 can be used.

As the trimeric isocyanate catalyst, for example, a metal salt of an aliphatic carboxylic acid, a phenolate such as potassium phenate, or a 2,4,6-tris(dimethylaminomethyl)phenol, 2, 4 may be used. - bis(dimethylaminomethyl)phenol, 2,6-di-t-butyl-4-dimethylaminotrimethyldecanephenol, triethylamine, N,N',N"-three An amine compound such as (dimethylaminopropyl)hexahydro-S-triazine or diazabicycloundecene, wherein a metal salt of an aliphatic carboxylic acid such as acetic acid or propionic acid is preferred. The sodium, potassium, and tin salts of carboxylic acids such as undecanoic acid, caproic acid, caprylic acid, and myristic acid are ideal. Further, as a commercial product, 2-hydroxypropyltrimethylammonium may also be used. Octanoic acid salt (DABCO TMR, manufactured by Air Products Japan Co., Ltd.), potassium octoate (DABCO K-15, manufactured by air products Japan).

As described above, the polyisocyanate of the present invention can be produced by a method of simultaneously performing allophanation and trimerization, or a stepwise process of allophanation and trimerization, and the present invention The most desirable method is a simultaneous method of allophanation and trimerization.

At this time, as a catalyst, it is easy to carry out reaction control, and among the various catalysts, tin octylate is an ideal user.

Further, the polyisocyanate may be used in combination of two or more kinds. In this case, the mixture may be partially used to satisfy the above allophanate group at a molar ratio satisfying the above allophanate group and the trimer isocyanate group. Polyisocyanate with a molar ratio of a trimeric isocyanate group.

The viscosity of the polyisocyanate used in the present invention is not particularly limited, and is generally 2,000 mPa ‧ or less at 25 ° C, preferably 1,500 mPa ‧ s or less, and more preferably 1,000 mPa ‧ s or less. When the viscosity of the polyisocyanate exceeds 2,000 mPa ‧ s, the viscosity of the coating composition becomes high, resulting in difficulty in use. Further, the lower limit of the viscosity is not particularly limited, and it is generally considered to be 50 mPa·s or more from the viewpoint of use.

Since the coating composition of the present invention is characterized by the above-mentioned polyisocyanate, the other component which is subjected to reaction hardening therewith may be appropriately selected from the polyol compounds used in the application.

Specifically, for example, an acrylic polyol or a fluorine-based polyol, and in consideration of weather resistance, a fluorine-based polyol is preferable, and a balance between weather resistance and cost is considered, and acrylic acid is used. Polyol is suitable.

Further, in the present invention, it is preferable that the polyol compound is soluble in a low-polar organic solvent from the viewpoint of the properties of the polyisocyanate which is excellent in solubility in a low-polar organic solvent.

The acrylic polyol which is soluble in the low-polar organic solvent is not particularly limited, and a known weak solvent-soluble acrylic polyol can be generally used. As such a specific example, ACRYDIC HU-596 (made by Dainippon Ink Chemical Industry Co., Ltd.), EXXELOR 410 (made by Asia Industrial (share)), and Hitarloy 6500 (Hitachi Chemical Industry Co., Ltd.) Shares)) and other examples.

The fluorine-based polyol which is soluble in the low-polar organic solvent is not particularly limited, and a known weak solvent-soluble fluorine-based polyol can be generally used. Specific examples thereof include a fluoroethylene-vinyl ether (vinyl ester) copolymer and the like. Commercial products such as Lumiflon LF800 (Asahi Glass Co., Ltd.) and the like.

The hydroxyl value and the acid value of the polyol compound are not particularly limited, and in the coating material of the present invention, the hydroxyl group is preferably from 1 to 300 mgKOH/g, more preferably from 1 to 250 mgKOH/g. When the valence of the hydroxyl group is less than 1 mgKOH/g, the crosslinking of the coating film is insufficient, so that the physical properties such as the strength of the coating film tend to decrease. When the temperature exceeds 300 mgKOH/g, the crosslinking density of the coating film becomes too high to become too hard. The followability and softness of the material are reduced.

Further, 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, in view of the strength of the obtained coating film and the usability of the coating material. The number average molecular weight is a measured value (polystyrene equivalent value) measured by gel permeation chromatography (GPC) detected by a scanning refractometer.

The blending ratio of the polyisocyanate composition to the polyol compound in the coating composition of the present invention is preferably from 1 to 150 parts by mass of the polyisocyanate composition per 100 parts by mass of the polyol, preferably from 1 to 130 parts by mass. More preferably, it is 1 to 100 parts by mass.

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

Further, the low-polarity organic solvent may be added to the polyol composition when it is added, and may be added to the mixture of the polyisocyanate composition and the polyol.

Here, the "aniline point" means the lowest temperature at which an equal volume of aniline and a sample (organic solvent) are present as a homogeneous mixed solution. Further, the "mixed aniline point" means the volume of the aniline 2, the volume of the sample 1 and the volume of 1-heptane 1 as the lowest temperature at which the homogeneous mixed solution is present. The aniline point and the mixed aniline point can be determined based on the aniline point and mixed aniline point test method contained in JIS K 2256.

Further, since the freezing point of aniline is -6 ° C, the aniline point cannot be measured at the following temperature. Therefore, heptane is mixed with aniline, and the mixed aniline point is used in order to measure the solubility of the organic solvent over a wider range.

The aniline point is preferably from 10 to 70 ° C, preferably from 10 to 60 ° C, more preferably from 10 to 50 ° C. Further, it is preferred that the mixed aniline point is 5 to 50 °C. When the aniline point is less than 10 ° C, or the mixed aniline point is less than 5 ° C, the substrate is easily eroded, the aniline point exceeds 70 ° C, or the mixed aniline point exceeds 50 ° C to dissolve the polyisocyanate of the present invention.

Examples of the organic solvent include methylcyclohexane (aniline point: 40 ° C), ethyl cyclohexane (aniline point: 44 ° C), petroleum solvent (aniline point: 56 ° C), and turpentine (aniline point: In the case of 44 ° C), a petroleum-based hydrocarbon is commercially available, High Aromatic White Spirit (HAWS) (manufactured by Shell Chemicals Japan, benzene base: 17 ° C), and Low Aromatic White Spirit (LAWS) (manufactured by Shell Chemicals Japan). Aniline point: 44 ° C), Esso naphtha No. 6 (manufactured by Exxon Mobile Co., Ltd., aniline point: 43 ° C), Pegasol 3040 (manufactured by Exxon Mobile Co., Ltd., aniline point: 55 ° C), A solvent (manufactured by Nippon Oil Co., Ltd., aniline) Point: 45 ° C), Cleansol (manufactured by Nippon Oil Co., Ltd., aniline point: 64 ° C), petroleum solvent A (manufactured by Nippon Oil Co., Ltd., aniline point: 43 ° C), HIAROM 2S (manufactured by Nippon Oil Co., Ltd., aniline point: 44 ° C), Solvesso 100 (manufactured by exxon mobile, mixed aniline point: 14 ° C), Solvesso 150 (exxon mobile company, mixed aniline point: 18.3 ° C), Swasol 100 (Maruzon Petrochemical Co., Ltd., mixed aniline point: 24.6 °C), Swasol 200 (Maruzon Petrochemical Co., Ltd., mixed aniline point 23.8°C), Swasol 1000 (made by Maruzen Petrochemical Co., Ltd., mixed aniline point: 12.7 °C), Swasol 1500 (made by Maruzen Petrochemical Co., Ltd., mixed benzene base: 16.5 °C), Swasol 1800 (made by Maruzen Petrochemical Co., Ltd., mixed aniline point) :15.7 ° C), Ignition IPZOLE 100 (manufactured by Idemitsu Kosan Co., Ltd., mixed aniline point: 13.5 ° C), IPZOLE 150 (manufactured by Idemitsu Kosan Co., Ltd., mixed benzene base: 15.2 ° C), Pegasol ARO-80 (exxon mobile company, Mixed aniline point: 25 ° C), Pegasol R-100 (exxon mobile company, mixed aniline point: 14 ° C), Akashi Hymos (manufactured by Shell Chemicals Japan, mixed aniline point: 12.6 ° C), Nikko Hysol (New Japan Oil company company, mixed aniline point: 17 ° C or less) and other examples. These organic solvents may be used alone or in combination of two or more.

An organic solvent having an aniline point of 10 ° C or more or a mixed aniline point of 5 ° C or more has a characteristic of low odor. Therefore, the coating composition of the present invention containing the low polar organic solvent is also desirable from the viewpoint of environmental resistance.

Further, since the low-polarity organic solvent has a low dissolving power and is less likely to erode the substrate, the coating composition can be repeatedly applied, and is also suitable for a coating material for repair.

In addition, the coating composition may also contain various additives generally used in coatings. As an additive, for example, a plasticizer, a preservative, an antifungal agent, an algicide, an antifoaming agent, a leveling agent, a pigment dispersant, a sedimentation inhibitor, an anti-dripping agent, a catalyst, a hardening accelerator, and dehydration Examples of agents, deluters, ultraviolet absorbers, antioxidants, pigments, surfactants, and the like.

When the coating film is prepared from the coating composition of the present invention, it can be applied to a suitable substrate such as concrete, mortar, siding board, extruded sheet, tile, metal, glass, wood, plastic, etc. It can be applied by a method such as roll coating or spray coating, and dried and cured by an appropriate method.

Further, when the dry building material is coated, it may be pre-coated in a factory or the like via a flow coating or a roll coating.

Further, the coating composition may be directly applied to a substrate and applied by caulking, electrodeposition, primer (primer coating), or intermediate coating (coloring, etc.). Further, when the substrate is a metal, it may be applied to a surface treatment such as an iron phosphate treatment or a zinc phosphate treatment.

Hereinafter, the present invention will be more specifically described by way of examples and comparative examples, but the present invention is not limited by the following examples. In addition, below, the viscosity is a measured value of a B-type rotational viscometer.

[1] Manufacture of polyisocyanate [Example 1]

880 g of hexamethylene diisocyanate (manufactured by Japan Polyurethane Industry Co., Ltd., NCO content: 49.9) was placed in a four-liter four-necked flask equipped with a stirrer, a thermometer, a cooling tube, and a nitrogen gas introduction tube. The mass%, hereinafter referred to as HDI), and 120 g of tridecyl alcohol (manufactured by Kyowa Fermentation Co., Ltd.) were stirred and heated to 85 ° C to carry out a urethanization reaction for 3 hours.

Then, 0.1 g of the allophanate and the trimeric isocyanate catalyst tin octylate (manufactured by Nippon Chemical Industry Co., Ltd.) were added to the reaction liquid, and the reaction was carried out at 110 ° C until the specific NCO content was reached. An acid phosphate (JP-508, manufactured by Seongbuk Chemical Industry Co., Ltd.) of 0.4 g of a reaction stopper was added, and the reaction was stopped at 50 ° C for 1 hour.

Thus, the reaction product was removed, and excess HDI was removed by thin film distillation (condition: 140 ° C, 0.04 kPa) to obtain a modified polyisocyanate having an NCO content of 15.8% by mass, a viscosity (25 ° C) of 320 mPa ‧ and a free HDI content of 0.1% by mass. S-1).

[Examples 2 to 4]

The modified polyisocyanate S-2 to S-4 were obtained in the same manner as in Example 1 except that the amount of the catalyst or the like shown in Table 1 was changed and the NCO content was changed.

[Example 5]

850 g of HDI (manufactured by Nippon Polyurethane Industry Co., Ltd., NCO content: 49.9 mass%) was placed in a four-necked flask equipped with a stirrer, a thermometer, a cooling tube, and a nitrogen gas introduction tube. And 150 g of KALCOL 200GD (2-octyldodecanol, manufactured by Kao Co., Ltd.), which was stirred while heating to 85 ° C for urethanization for 3 hours.

Then, in this reaction, 0.2 g of the allophanate and the trimeric isocyanate catalyst tin octylate (manufactured by Nippon Chemical Industry Co., Ltd.) were added, and the reaction was carried out at 110 ° C until the specific NCO content was reached. An acid phosphate (JP-508, manufactured by Seongbuk Chemical Industry Co., Ltd.) of 0.8 g of a reaction stopper was added, and the reaction was stopped at 50 ° C for 1 hour.

Thus, the reaction product was removed by excess HDI by thin film distillation (condition: 140 ° C, 0.04 kPa) to obtain a modified polyisocyanate S having an NCO content of 15.7 mass%, a viscosity (25 ° C) of 560 mPa ‧ and a free HDI content of 0.2 mass %. -5.

[Embodiment 6]

The modified polyisocyanate S-6 was obtained in the same manner as in Example 5 except that the amount of the catalyst or the like shown in Table 1 was changed and the NCO content was changed.

[Comparative Example 1]

850 g of HDI and 150 g of KALCOL 200GD (2-octyldodecanol, Kao) were placed in a four-necked flask equipped with a stirrer, a thermometer, a cooling tube, and a nitrogen gas introduction tube. This was stirred while heating to 85 ° C for urethanization for 3 hours.

Then, 0.4 g of the allophanate and the trimeric isocyanate catalyst tin octylate (manufactured by Nippon Chemical Industry Co., Ltd.) were added to the reaction liquid, and the reaction was carried out at 110 ° C to reach a specific NCO content. Thereafter, 2.0 g of an acid phosphate (JP-508, manufactured by Seongbuk Chemical Industry Co., Ltd.) of a reaction stopper was added, and the reaction was stopped at 50 ° C for 1 hour.

From the reaction product, excess HDI by thin film distillation (condition: 140 ° C, 0.04 kPa) was removed to obtain a modified poly having an NCO content of 15.3% by mass, a viscosity (25 ° C) of 2,500 mPa ‧ and a free HDI content of 0.1% by mass. Isocyanate H-1.

[Comparative Example 2]

880 g of HDI and 120 g of tridecyl alcohol (manufactured by Kyowa Fermentation Co., Ltd.) were placed in a four-necked flask equipped with a stirrer, a thermometer, a cooling tube, and a nitrogen inlet tube, and stirred. At the same time, it was heated to 85 ° C and subjected to urethane for 3 hours.

Then, 0.1 g of the allophanate catalyst zirconium octoate (manufactured by the first dilute element chemical industry (manufactured by Shimizu Co., Ltd.) was added to the reaction liquid, and the reaction was carried out at 110 ° C to reach a specific NCO content, and then 0.2 was added. The acid phosphate (JP-508, manufactured by Seongbuk Chemical Industry Co., Ltd.) of the reaction inhibitor of g was stopped at 50 ° C for 1 hour.

From the reaction product, excess HDI was removed by thin film distillation (condition: 140 ° C, 0.04 kPa) to obtain an NCO content of 14.8% by mass and a viscosity (25 ° C) of 130 mPa. s, modified polyisocyanate H-2 having a free HDI content of 0.1% by mass.

[Comparative Example 3]

In a four-necked flask equipped with a stirrer, a thermometer, a cooling tube, and a nitrogen inlet tube, 910 g of HDI, 90 g of 2-ethylhexanol, and immediately heated to 80 ° C for urethane Esterification for 2 hours.

After that, add 0. ig of the trimeric isocyanate catalyst 2-hydroxypropyltrimethylammonium. Octanoic acid salt (DABCO TMR, manufactured by Air Products Japan), reacted at 80 ° C to reach a specific NCO content, and then added 0.8 g of the acid phosphate of the reaction stopper (JP-508, Seongbuk Chemical Industry Co., Ltd. )), the reaction was stopped at 50 ° C for 1 hour.

From the reaction product, excess HDI was removed by thin film distillation (condition: 130 ° C, 0.04 kPa) to obtain an NCO content of 19.1% by mass and a viscosity (25 ° C) of 700 mPa. s, a modified polyisocyanate H-3 having a free HDI content of 0.2% by mass.

[Embodiment 7]

Into a four-necked flask equipped with a stirrer, a thermometer, a cooling tube, and a nitrogen gas introduction tube, 130 g of the polyisocyanate S-4 obtained in the fourth embodiment and 70 g of the comparative example 2 were placed. The polyisocyanate H-2 was stirred and mixed for 1 hour to obtain an NCO content of 16.0% by mass and a viscosity (25 ° C) of 240 mPa. s, free HDI content of 0.2% by mass Modified polyisocyanate S-7.

[Comparative Example 4]

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

With respect to each of the polyisocyanates obtained in Examples 1 to 7 and Comparative Examples 1 to 4, each of the allophanate groups, the trimer isocyanate groups, and the urethane groups was measured by the following method. ) Moerby. The results are shown in Table 1.

[assay]

¹ H-NMR (Gemini 2000 (300 MHz) manufactured by Varian, a hydrogen atom bonded to a nitrogen atom of an allophanate group in the vicinity of 8.5 ppm, and a nitrogen atom adjacent to a trimeric isocyanate group in the vicinity of 3.7 ppm) The area ratio of the hydrogen atom of the methylene group and the hydrogen atom of the nitrogen atom bonded to the urethane of 7.0 ppm is determined. The specific measurement conditions are as follows.

Measuring temperature: 23 ° C

Sample concentration: 0.1g/1ml

Total number of times: 32 times

Moderate time: 5 seconds

Solvent: Dihydrodimethyl hydrazine

Chemical shift reference: hydrogen atom symbol of methyl dimethyl hydrazine (2.5 ppm)

Further, the solubility of each of the polyisocyanates obtained in Examples 1 to 7 and Comparative Examples 1 to 4 at 20 ° C for petroleum solvent A (manufactured by Nippon Oil Co., Ltd.) was measured by the following method. The results are shown in Table 1.

[assay]

1 g of polyisocyanate was weighed, and petroleum solvent A was added thereto, and when it was turbid, an end point was obtained, and the amount (g) of the petroleum solvent A added at this time was determined.

Using the added amount, the tolerance is calculated by the following formula (1).

Tolerance = required amount of organic solvent (g) / sampled amount (1g) (1)

Ethyl carbamate ratio: ratio of the total amount of allophanate groups and trimeric isocyanate groups to 100

[2] Manufacture of two-component coating composition [Examples 8 to 14 and Comparative Examples 5 to 8]

According to the ratios shown in Table 2, each of the polyisocyanate obtained in Examples 1 to 7 and Comparative Examples 1 to 4 and petroleum solvent A (manufactured by Nippon Oil Co., Ltd.) (polyisocyanate composition) and acrylic polyol (ACRYDIC HU) were blended. -596, Dainippon Ink Chemical Industry Co., Ltd., titanium oxide (CR-90, Ishihara Industry Co., Ltd.), and petroleum solvent A (Nippon Oil Co., Ltd.), prepared into a two-component coating composition Things.

The two-component coating compositions prepared in Examples 8 to 14 and Comparative Examples 6 and 8 were each treated with methyl ethyl ketone on degreased steel sheets (JIS G 3141 trade name SPCC-SB, PF-1077, Japan test panel industry). In the (share) system, the coating was applied at a wet film thickness of 100 μm using a thin coater, and the solution was grown for 7 days in an environment of a temperature of 20 ° C and a relative humidity of 65% to form a dry film thickness of 40 to 50 μm. Coating film. The following characteristics were evaluated for the obtained coating film. The results are shown in Table 3.

Further, in the two-liquid type coating composition prepared in Comparative Examples 5 and 7, since the tolerance to the low-polarity solvent was insufficient, the test could not be performed.

(1) Bending resistance

According to the bending resistance test of JIS K-5600-5-1:1999, the cylindrical mold core with a diameter of 2 mm was used to evaluate whether the coating film was cut when bent through the cylindrical mold core, and whether the steel plate was Peeling occurred. If there is no film splitting or peeling, it is judged as qualified.

(2) Resistance to concave pressure

According to the dent-resistance test of JIS K-5600-5-2:1999, the extrusion was used to evaluate whether or not the coating film was partially deformed by extrusion, and whether the steel sheet was peeled off. The extrusion depth (mm) produced by the slitting and peeling of the coating film through the extruder is used as the recession resistance.

(3) Heavy hammer drop resistance

According to the weight drop test of JIS K-5600-5-3:1999, the weight of 10.3 mm and the weight of 0.5 kg is used to evaluate whether the film is split when the weight is dropped by the weight, and Whether the steel sheet peels off. The minimum drop height (cm) at which the coating film is split and peeled off is used as the weight drop resistance.

(4) Coating hardness

The hardness of the surface of the coating film was measured in accordance with the scratch hardness test (pencil method) of JIS K-5600-5-4:1999. The hardest pencil hardness at which no trace was formed on the surface of the coating film was taken as the hardness of the coating film.

(5) Adhesion

The adhesion of the coating film is based on JIS K-5600-5-6:1999. The checkerboard tape peeling test is based on JIS K-5600-5-6:1999. The lattice pattern of the right angle is cut into the coating film, and the peeling of the substrate from the substrate is evaluated. Method) The resistance of the film.

As shown in Table 3, the coating films obtained from the coating compositions of Examples 8 to 14 had good hardness, and also showed that all other characteristics were good.

Claims (5)

A polyisocyanate composition characterized by comprising: hexamethylene diisocyanate and an aliphatic monoalcohol having a carbon number of 11 to 20 in the presence of a tin octoate catalyst, simultaneously performing an allophanation reaction and a trimeric isocyanation The polyisocyanate obtained by the reaction and the low polar organic solvent having an aniline point of 10 to 70 ° C or a low polar organic solvent having a mixed aniline point of 5 to 50 ° C, the polyisocyanate having an allophanate group in the molecule, and three The polyisocyanate group and the urethane group, and the molar ratio of the allophanate group to the trimer isocyanate group is an allophanate group/trimeric isocyanate group = 69/31 to 30/70. The polyisocyanate composition of claim 1, wherein the allophanate group and the trimer isocyanate group have an allophanate group/trimeric isocyanate group = 60/40 to 30/70. A method for producing a polyisocyanate, which comprises simultaneously reacting a hexamethylene diisocyanate with an aliphatic monohydric alcohol having a carbon number of 11 to 20 in the presence of a tin octanoate catalyst, and simultaneously performing an allophanation reaction and a trimeric isocyanation reaction. A method for producing a polyisocyanate, characterized in that the polyisocyanate has an allophanate group, a trimeric isocyanate group and a urethane group in the molecule, and the allophanate group and the trimer isocyanate group The molar ratio is allophanate/trimeric isocyanate = 69/31 to 30/70. The method for producing a polyisocyanate according to claim 3, wherein the molar ratio of the allophanate group to the trimeric isocyanate group is Allophanate/trimeric isocyanate = 60/40~30/70. A two-liquid type coating composition characterized by comprising the polyisocyanate composition of claim 1 or 2 and a polyol compound.