JPWO2009044595A1 - Two-component fluorine-containing coating composition - Google Patents

Abstract

A two-pack type fluorine-containing coating composition comprising a main agent containing a fluorine-containing polyol and a curing agent containing a polyisocyanate, wherein the main agent and / or the curing agent is an organic solvent having an aniline point of 70 ° C. or lower, Alternatively, it contains an organic solvent having a mixed aniline point of 5 to 50 ° C., the fluorine-containing polyol is soluble in the organic solvent, and the polyisocyanate reacts with an aliphatic diisocyanate and a monoalcohol having 1 to 20 carbon atoms. A two-component fluorine-containing coating composition containing an aliphatic polyisocyanate and having a molar ratio of allophanate groups to isocyanurate groups in the polyisocyanate of 100: 0 to 90:10.

Description

  The present invention relates to a two-component fluorine-containing coating composition.

  Urethane-based paints using polyisocyanates derived from aliphatic or alicyclic diisocyanates are excellent in weather resistance and abrasion resistance, coating outdoor base materials such as buildings and civil engineering structures, repairing automobiles, Used for plastic coating.

However, in recent years, the required characteristics in these coating fields have become more severe, and further improvement in weather resistance is required. Therefore, it has been studied to use a fluorine-containing polyol having excellent weather resistance. For example, Patent Document 1 discloses a two-component fluorine-containing coating composition containing a fluorine-containing polyol and a polyisocyanate.
Japanese Patent No. 3244297

  In the two-pack type fluorinated coating composition disclosed in the cited document 1, although the weather resistance is improved, the formed coating film tends to be uneven and non-uniform and the coating film appearance tends to deteriorate. The mechanical strength of the steel may also decrease.

  Accordingly, an object of the present invention is to provide a two-pack type fluorine-containing coating composition capable of forming a coating film having a sufficiently good coating film appearance and sufficiently excellent weather resistance.

  The present invention is a two-pack type fluorine-containing coating composition comprising a main agent containing a fluorine-containing polyol and a curing agent containing a polyisocyanate, and the main agent and / or the curing agent has an aniline point of 70 ° C. or less. A certain organic solvent or an organic solvent having a mixed aniline point of 5 to 50 ° C. is contained, the fluorine-containing polyol is soluble in the organic solvent, and the polyisocyanate is an aliphatic diisocyanate and a C 1-20 monocarbon. Provided is a two-component fluorine-containing coating composition containing an aliphatic polyisocyanate obtained by reacting with an alcohol and having a molar ratio of allophanate groups to isocyanurate groups in the polyisocyanate of 100: 0 to 90:10. To do.

  By using a two-pack type fluorine-containing coating composition having the above-described configuration, it is possible to form a coating film having a sufficiently good coating film appearance and sufficiently excellent weather resistance. Here, although the present inventors are not restrained by a specific theory, it is guessed as follows about the reason which the said effect is acquired.

  That is, the two-pack type fluorine-containing coating composition of the present invention is a combination of a fluorine-containing polyol having excellent weather resistance and a polyisocyanate having a molar ratio of allophanate groups to isocyanurate groups within the above range. By making the fluorine-containing polyol a predetermined one, the compatibility between the two is improved. Furthermore, at least one of the main agent or the curing agent contains an organic solvent having an aniline point of 70 ° C. or lower, or an organic solvent having a mixed aniline point of 5 to 50 ° C., so that the polyisocyanate and the fluorinated polyol are uniformly obtained. Dissolved solution. Therefore, it is speculated that the coating film to be formed has a uniform appearance with no unevenness, the coating film appearance is sufficiently good, and the weather resistance is further improved. Moreover, since the organic solvent whose aniline point is 70 degrees C or less, or the organic solvent whose mixed aniline point is 5-50 degreeC has a low odor and is an environmentally friendly solvent, the two-pack type fluorine-containing coating of this invention The agent is also useful in terms of environmental resistance.

  The polyisocyanate preferably contains an aliphatic polyisocyanate obtained by reacting an aliphatic diisocyanate with a monoalcohol having 3 to 20 carbon atoms. Such a polyisocyanate has improved solubility in a low-polar organic solvent, and thus a two-component fluorine-containing coating composition containing the polyisocyanate can form a coating film that is more excellent in coating film appearance and weather resistance.

  The polyisocyanate preferably has a viscosity at 25 ° C. of 2000 mPa · s or less. Thereby, the two-pack type fluorine-containing coating composition can be easily handled, and can form a coating film that is further excellent in coating film appearance and weather resistance.

  According to the present invention, it is possible to provide a two-pack type fluorinated coating composition capable of forming a coating film having a sufficiently good coating film appearance and sufficiently excellent weather resistance.

  Hereinafter, preferred embodiments of the present invention will be described in detail.

  The two-component fluorine-containing coating composition of the present invention is composed of a main agent containing a fluorine-containing polyol and a curing agent containing a polyisocyanate.

  First, the fluorine-containing polyol contained in the main agent will be described. In the two-component fluorine-containing coating composition of the present invention, the fluorine-containing polyol needs to be soluble in an organic solvent having an aniline point of 70 ° C. or less, which will be described later.

Here, it can be judged by tolerance whether the fluorine-containing polyol is soluble in the organic solvent. That is, 5 g of fluorine-containing polyol was weighed out, the organic solvent was added thereto, the turbid portion was taken as the end point, the required amount (mL) of the organic solvent at that time was obtained, and the tolerance was calculated from the following formula (1). . Higher tolerance means better solubility in the organic solvent. When the tolerance of the fluorine-containing polyol is less than 0.1 mL / g, it means that the fluorine-containing polyol is not soluble in the organic solvent. The tolerance is 0.1 mL / g or more, preferably 1.0 mL / g or more, and more preferably 5.0 mL / g or more.
Tolerance = Required amount of organic solvent (mL) / Sample amount (5 g) (1)

  The fluorine-containing polyol is obtained by copolymerizing a fluorine-containing monomer and a monomer having a hydroxyl group as essential components. The fluorine-containing monomer is preferably a fluoroolefin, and examples thereof include tetrafluoroethylene, chlorotrifluoroethylene, trichlorofluoroethylene, hexafluoropropylene, vinylidene fluoride, vinyl fluoride, and trifluoromethyltrifluoroethylene. it can.

  Examples of the monomer having a hydroxyl group include hydroxyalkyl vinyl ethers such as hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether and cyclohexanediol monovinyl ether; hydroxyalkyl allyl ethers such as 2-hydroxyethyl allyl ether; Examples thereof include monomers having a hydroxyl group, such as hydroxyl group-containing vinyl carboxylate or allyl ester.

  The fluorine-containing polyol may be copolymerized with other monomers in addition to the fluorine-containing monomer and the monomer having a hydroxyl group. As other monomers, vinyl monomers can be used.

  Examples of vinyl monomers include vinyl ether, allyl ether, carboxylic acid vinyl ester, carboxylic acid allyl ester, and olefin. Of these, vinyl ethers and carboxylic acid vinyl esters are preferred as the vinyl monomer.

  Examples of the vinyl ether include alkyl vinyl ethers such as cyclohexyl vinyl ether, such as cycloalkyl vinyl ether, nonyl vinyl ether, 2-ethylhexyl vinyl ether, hexyl vinyl ether, n-butyl vinyl ether, and tert-butyl vinyl ether. Examples of allyl ethers include alkyl allyl ethers such as ethyl allyl ether and hexyl allyl ether.

  Examples of the carboxylic acid vinyl ester and carboxylic acid allyl ester include vinyl or allyl esters of carboxylic acids such as acetic acid, butyric acid, pivalic acid, crotonic acid, benzoic acid, and maleic acid. Examples of olefins include ethylene and isobutylene.

  From the viewpoint of further improving the solubility in the organic solvent, the fluorinated polyol is preferably a trichlorofluoroethylene-based fluorinated polyol. Such a fluorine-containing polyol is also available as a commercial product, and for example, Lumiflon LF800 (trade name, manufactured by Asahi Glass Co., Ltd.) can be used.

  Moreover, from the viewpoint of improving the solubility in the organic solvent, the fluorine-containing polyol preferably has a hydroxyl value of 1 to 300 mgKOH / g, more preferably 1 to 250 mgKOH / g. 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. When the hydroxyl value exceeds 300 mg KOH / g, the crosslinking density of the coating film becomes too high and hard. Followability and flexibility tend to be reduced.

  Next, polyisocyanate contained in the curing agent will be described. The polyisocyanate contains an aliphatic polyisocyanate obtained by reacting an aliphatic diisocyanate with a monoalcohol having 1 to 20 carbon atoms as an essential component.

  Examples of the aliphatic diisocyanate include tetramethylene diisocyanate, hexamethylene diisocyanate, decamethylene diisocyanate, and lysine diisocyanate. These can be used individually by 1 type or in mixture of 2 or more types.

  The monool that reacts with the aliphatic diisocyanate preferably has 1 to 20 carbon atoms, more preferably 3 to 20 carbon atoms, and still more preferably 3 to 18 carbon atoms. Examples of such monools include n-propanol, iso-propanol, n-butanol, iso-butanol, n-pentanol, iso-pentanol, n-hexanol, n-heptanol, n-octanol, 2 -Ethylhexanol, ethyldimethyl-1-hexanol, methyl-1-nonanol, dimethyl-1-octanol, tetramethyl-1-hexanol, 3-ethyl-4,5,6-trimethyloctanol, 4,5,6,7 -Tetramethylnonanol, 4,5,8-trimethyldecanol, 4,7,8-trimethyldecanol, tridecanol, tetradecanol, 2-hexyldodecanol, 2-octyldodecanol, 2-dodecyldecanol, 2-hexadecyl octadecanol is mentioned. These can be used individually by 1 type or in mixture of 2 or more types.

  The aliphatic polyisocyanate can be synthesized by reacting the aliphatic diisocyanate with the monool in the presence of an allophanatization catalyst. As a synthesis method, for example, a method described in Japanese Patent No. 3511622 can be used.

  As the allophanatization catalyst, for example, zirconium salt of carboxylic acid can be used. Examples of the carboxylic acid include acetic acid, propionic acid, butyric acid, caproic acid, octylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, 2-ethylhexanoic acid and other saturated aliphatic carboxylic acids, 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 carboxylic acids such as naphthenic acid, oleic acid, linoleic acid , Monocarboxylic acids such as linolenic acid, soybean oil fatty acid, unsaturated aliphatic carboxylic acid such as tall oil fatty acid, aromatic aliphatic carboxylic acid such as diphenylacetic acid, aromatic carboxylic acid such as benzoic acid, 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, kurtaconic acid, azelaic acid, sebacic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, 1,4-cyclohexyldicarboxylic acid, α-hydromuconic acid, β-hydromcon And polycarboxylic acids such as acid, α-butyl-α-ethylglutaric acid, 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, and it is more preferable to use a monocarboxylic acid zirconium salt having 10 or less carbon atoms.

  In addition, although the aliphatic polyisocyanate obtained in this way mainly has allophanate groups, it can also have an isocyanurate group by adjusting the reaction conditions. The molar ratio of allophanate groups and isocyanurate groups in the aliphatic polyisocyanate can be adjusted in the range of 100: 0 to 70:30.

In the two-component fluorine-containing coating composition of the present invention, the molar ratio of allophanate groups to isocyanurate groups in the polyisocyanate contained as a curing agent is 100: 0 to 90:10, and 99.9: 0.1. More preferably, it is -90: 10. When this molar ratio exceeds 90:10, the solubility in the organic solvent tends to decrease. The molar ratio can be calculated by measuring ¹ H-NMR of polyisocyanate.

  In addition, the said molar ratio can also be prepared in the suitable range by synthesize | combining the polyisocyanate which has an isocyanurate group separately, and containing in polyisocyanate with aliphatic polyisocyanate.

  The polyisocyanate having an isocyanurate group can be synthesized, for example, by modifying diisocyanate (such as trimerization) in the presence of an isocyanurate-forming catalyst. As such a modification method, for example, methods described in Japanese Patent Nos. 3371480 and 2002-241458 can be used.

  As the diisocyanate, it is preferable to use an aliphatic polyisocyanate or an alicyclic diisocyanate from the viewpoint of weather resistance. For example, aliphatic diisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, decamethylene diisocyanate, and lysine diisocyanate, isophorone diisocyanate Hydrogenated diphenylmethane diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated tetramethylxylylene diisocyanate, cyclohexane diisocyanate and the like can be used. These can be used individually by 1 type or in mixture of 2 or more types.

  Examples of the isocyanurate-forming catalyst include alkali metal salts of aliphatic carboxylic acids, phenolates such as potassium phenolate, 2,4,6-tris (dimethylaminomethyl) phenol, 2,4-bis (dimethylaminomethyl) phenol. Amines such as 2,6-di-t-butyl-4-dimethylaminotrimethylsilanephenol, triethylamine, N, N ′, N ″ -tris (dimethylaminopropyl) hexahydro-S-triazine, diazabicycloundecene System compounds can be used. Of these, alkali metal salts of aliphatic carboxylic acids are preferable, and examples thereof include sodium salts and potassium salts of carboxylic acids such as acetic acid, propionic acid, undecyl acid, capric acid, octylic acid, and myristic acid.

  The polyisocyanate contains an allophanate group, so that the solubility in an organic solvent having an aniline point of 70 ° C. or lower can be improved, and the viscosity of the two-component fluorine-containing coating composition can be lowered. It becomes easy. On the other hand, polyisocyanate can improve the heat resistance, chemical resistance and hardness of the resulting coating film by containing an isocyanurate group.

  The viscosity of the polyisocyanate is preferably 2000 mPa · s or less at 25 ° C., more preferably 1500 mPa · s or less, and still more preferably 1000 mPa · s or less. When the viscosity of the polyisocyanate exceeds 2000 mPa · s, the viscosity of the two-pack type fluorine-containing coating composition tends to be high and handling tends to be difficult. The lower limit of the viscosity is not particularly limited, but is preferably 50 mPa · s or more from the viewpoint of handling.

  In the two-component fluorine-containing coating composition of the present invention, the content of polyisocyanate contained as a curing agent is preferably 1 to 150 parts by mass with respect to 100 parts by mass of the fluorine-containing polyol contained as a main agent. 1 to 130 parts by mass, more preferably 1 to 100 parts by mass.

  In the two-component fluorine-containing coating composition of the present invention, the main agent and / or curing agent contains an organic solvent having an aniline point of 70 ° C. or lower, or an organic solvent having a mixed aniline point of 5 to 50 ° C. The organic solvent may be added at the time of preparing the main agent and / or the curing agent, or may be added later for viscosity adjustment at the time of mixing the main agent and the curing agent. In the present invention, it is more preferable that the main agent contains a fluorinated polyol and the organic solvent.

  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 the 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, the mixed aniline point is used to measure the solvent power of the organic solvent more broadly by mixing heptane with aniline.

  The aniline point is preferably 10 to 70 ° C, more preferably 10 to 60 ° C, and still more preferably 10 to 50 ° C. In the case of a mixed aniline point, it is preferably 5 to 50 ° C. 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 attacked. If the aniline point exceeds 70 ° C. or the mixed aniline point exceeds 50 ° C., it becomes difficult to dissolve the polyisocyanate.

  Examples of such organic solvents include turpentine oil (aniline point: 20 ° C.), methylcyclohexane (aniline point: 40 ° C.), ethylcyclohexane (aniline point: 44 ° C.), and mineral spirit (aniline point: 56 ° C.). In addition, under the trade name marketed as petroleum-based hydrocarbons, High Aromatic White Spirit (hereinafter referred to as “HAWS”) (manufactured by Shell Chemicals Japan, aniline point: 17 ° C.), Low Aromatic White Spirit (hereinafter referred to as “Haromatic White Spirit”) , “LAWS”) (manufactured by Shell Chemicals Japan, aniline point: 44 ° C.), Essonaphtha No. 6 (ExxonMobil, aniline point: 43 ° C), Pegasol 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.), SWAZOL 310 (Maruzen Petrochemical Co., Ltd.) Manufactured, aniline point: 16 ° C), Solvesso 100 (manufactured by ExxonMobil, mixed aniline point: 14 ° C), Solvesso 150 (manufactured by ExxonMobil, mixed aniline point: 18.3 ° C), SWAZOL 100 (Maruzen Petrochemical Co., Ltd.) Manufactured, mixed aniline point: 24.6 ° C), SWAZOL 200 (manufactured by Maruzen Petrochemical Co., Ltd., mixed aniline point: 23.8 ° C), SWAZOL 1 00 (Maruzen Petrochemical Co., Ltd., mixed aniline point: 12.7 ° C.), Swazol 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 (produced by Idemitsu Kosan Co., Ltd., mixed aniline point: 13.5 ° C.), Idemitsu Ipsol 150 (produced by Idemitsu Kosan Co., Ltd., mixed aniline point: 15.2 ° C.), Pegasol ARO-80 (Exxon) Mobil Corp., mixed aniline point: 25 ° C), Pegasol R-100 (Exxon Mobil Corp., mixed aniline point: 14 ° C), Akashi Toshihizoru (manufactured by Shell Chemicals Japan, mixed aniline point: 12.6 ° C), NS It is below. 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 70 ° C. or lower or a mixed aniline point of 50 ° C. or lower has a feature that there is a limit to the dissolving power of various resins, and there is little odor. Therefore, the two-component fluorine-containing coating composition of the present invention is excellent from the viewpoint of environmental resistance. In addition, the organic solvent has a low dissolving power and does not easily attack the base, so that the two-component fluorine-containing coating composition can be repeatedly applied, and is useful as a paint for repair.

  The two-component fluorine-containing coating composition may contain various additives that can be used for general paints. 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 quenchers, ultraviolet absorbers, antioxidants, pigments, and surfactants.

  Moreover, as a coating method of the two-component fluorine-containing coating composition of the present invention, for example, methods such as brush coating, roller coating, spray coating and the like can be used. Moreover, when coating a dry-type building material, it is also possible to pre-coat in a factory etc. with a flow coater or a roll coater.

  Examples of the substrate to be applied include concrete, mortar, siding board, extruded plate, porcelain tile, metal, glass, wood, and plastic.

  The above-mentioned two-component fluorine-containing coating composition may be applied directly to the substrate, and it is iron phosphate when it is metal, the electrodeposition, undercoating (primer coating), intermediate coating (coloring, etc.) You may apply | coat on the base material with which surface treatments, such as a process or a zinc phosphate process, were given.

  As mentioned above, although preferred embodiment of this invention was described, this invention is not restrict | limited to this.

  Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited thereto.

[Synthesis of polyisocyanate]
(Synthesis Example 1)
Into a 1 L four-necked flask equipped with a stirrer, thermometer, condenser and nitrogen gas introduction tube, 950 g of hexamethylene diisocyanate (trade name “HDI”, isocyanate content: 49.9%, manufactured by Nippon Polyurethane Industry Co., Ltd.) and 50 g of isopropanol The mixture was heated to 85 ° C. with stirring and subjected to a urethanization reaction for 3 hours. Next, 0.1 g of zirconyl octylate (manufactured by Daiichi Rare Element Chemical Co., Ltd.) was added as an allophanatization catalyst to the reaction solution, and after reacting at 110 ° C. for 3 hours, a phosphate ester “JP-508” as a reaction terminator was used. (0.1 g of Johoku Chemical Co., Ltd., trade name) was added and stirred at 50 ° C. for 1 hour to stop the reaction. After completion of the reaction, the obtained reaction solution was subjected to thin-film distillation at 140 ° C. and 0.04 kPa, an isocyanate content of 19.3%, a viscosity at 25 ° C. of 100 mPa · s, unreacted free hexamethylene diisocyanate (hereinafter, A polyisocyanate having a content of 0.1% (denoted “F-HDI”) was obtained. This was designated as “S-1.”

(Synthesis Example 2)
Add 997 g of HDI, 2 g of 1,3-butanediol, and 1 g of phenol to a 1 L four-necked flask equipped with a stirrer, thermometer, condenser, and nitrogen gas inlet tube, and add 0.2 g of potassium caprate as an isocyanurate catalyst. After reaction at 50 ° C. for 1.5 hours, the temperature was immediately raised to 65 ° C. and reacted for 1 hour. When the isocyanate content reached 44.8%, 0.1 g of phosphoric acid as a reaction terminator was added and stirred for 1 hour to stop the reaction. After completion of the reaction, the resulting reaction solution was subjected to thin-film distillation at 130 ° C. and 0.04 kPa, with an isocyanate content of 23.2%, a viscosity at 25 ° C. of 1180 mPa · s, and an F-HDI content of 0.2%. A polyisocyanate was obtained. This was designated as “S-2”.

(Synthesis Example 3)
In a 1 L four-necked flask equipped with a stirrer, a thermometer, a cooler, and a nitrogen gas inlet tube, 900 g of the “S-1” and 100 g of the “S-2” are placed, and stirred and mixed at 25 ° C. for 2 hours. A polyisocyanate having an isocyanate content of 19.4% and a viscosity at 25 ° C. of 150 mPa · s was obtained. This was designated as “S-3”.

(Synthesis Example 4)
910 g of HDI and 90 g of 2-ethylhexanol were placed in a 1 L four-necked flask equipped with a stirrer, a thermometer, a cooler, and a nitrogen gas introduction tube, and heated to 85 ° C. with stirring to conduct a urethanization reaction for 3 hours. Next, 0.2 g of zirconyl octylate was added to this reaction liquid, and after reacting at 110 ° C. for 3 hours, 0.2 g of “JP-508” was added and stirred at 50 ° C. for 1 hour to stop the reaction. After completion of the reaction, the resulting reaction solution was subjected to thin-film distillation at 130 ° C. and 0.04 kPa to obtain a polyisocyanate having an isocyanate content of 16.8%, a viscosity at 25 ° C. of 120 mPa · s, and an F-HDI content of 0.1%. Isocyanate was obtained. This was designated as “S-4”.

(Synthesis Example 5)
In a 1 L four-necked flask equipped with a stirrer, a thermometer, a cooler, and a nitrogen gas introduction tube, 1000 g of the above “S-1” was added, and 1 g of potassium octylate was mixed with 4.5 g of dipropylene glycol and 45 g of tetrahydrofuran. 2 g of a solution dissolved in a solvent was added, and the mixture was stirred at 80 ° C. for 5 hours to carry out an isocyanuration reaction. Next, when the isocyanate content decreased by 2% from the addition of the catalyst, 0.2 g of phosphate ester was added and stirred at 50 ° C. for 1 hour to stop the reaction. A polyisocyanate having an isocyanate content of 17.3% and a viscosity at 25 ° C. of 300 mPa · s was obtained. This was designated as “S-5”.

(Synthesis Example 6)
In a 1 L four-necked flask equipped with a stirrer, a thermometer, a cooler, and a nitrogen gas introduction tube, 73 g of the “S-2”, 657 g of the “S-1” and “PP-1000” (polyether polyol) 270 g of Sanyo Kasei Kogyo Co., Ltd., trade name) was added, and a urethanization reaction was performed at 85 ° C. for 3 hours to obtain a polyisocyanate having an isocyanate content of 12.0% and a viscosity at 25 ° C. of 800 mPa · s. This was designated as “S-6”.

(Synthesis Example 7)
240 g of the “S-2” and 10 g of 2-ethylhexanol were placed in a 1 L four-necked flask equipped with a stirrer, a thermometer, a cooler, and a nitrogen gas introduction tube, and subjected to urethanization reaction at 85 ° C. for 3 hours. . Next, 750 g of the above “S-1” was added and stirred for 2 hours to obtain a polyisocyanate having an isocyanate content of 19.4% and a viscosity at 25 ° C. of 180 mPa · s. This was designated as “S-7”.

<NMR measurement>
¹ H-NMR of the polyisocyanate obtained in Synthesis Examples 1 to 7 was measured under the following conditions using a trade name “ECX400M” manufactured by JEOL Ltd. The molar ratio of allophanate and isocyanurate groups in the polyisocyanate is bound to the hydrogen signal adjacent to the nitrogen atom of the allophanate group near 8.55 ppm and to the methylene group adjacent to the nitrogen atom of the isocyanurate group near 3.85 ppm. It was calculated from the area ratio with the hydrogen signal. The results are shown in Table 1.
(Measurement condition)
Measuring solvent: deuterium chloroform,
Sample concentration: 0.1 g / 1 mL
Measurement temperature: 25 ° C
Number of integrations: 16 times Relaxation time: 5 seconds Chemical shift criteria: Hydrogen signal of deuterium chloroform is 7.24 ppm.

[Examples 1 to 5 and Comparative Example 1]
<Preparation of two-component fluorine-containing coating composition>
“Lumiflon LF800” (trade name, manufactured by Asahi Glass Co., Ltd.), which is a fluorine-containing polyol, and titanium oxide “CR-90” (trade name, manufactured by Ishihara Sangyo Co., Ltd.), which is a white pigment, with the composition (parts by mass) shown in Table 1. And an organic solvent “Mineral Spirit A” having an aniline point of 43 ° C. were mixed to prepare respective main agents. And the said polyisocyanate was mixed with the prepared main ingredient by the ratio (unit: mass part) shown in Table 2 as a hardening | curing agent, and the two-pack type fluorine-containing coating composition was prepared.

<Formation of coating film>
An applicator is applied to a 0.8 mm-thick steel plate (JIS G3141, manufactured by Nippon Test Panel Industry Co., Ltd., trade names “SPCC-SB”, PF-1077 treatment) obtained by degreasing the obtained two-component fluorine-containing coating composition with methyl ethyl ketone. Used with a thickness of 100 μm. After coating, the film was cured in an environment of 20 ° C. and 65% RH for 7 days to form a coating film having a dry film thickness of 40 to 50 μm.

<Evaluation of various performances>
The coating film produced as described above was evaluated by the following method.

(Compatibility)
In order to determine whether the fluorine-containing polyol and polyisocyanate are uniformly dissolved in “mineral spirit A”, which is a low-polar organic solvent, the compatibility in the two-component fluorine-containing coating composition is determined by using titanium oxide “CR- It was confirmed with the one prepared without adding "90".

(Appearance of coating film)
The appearance of the formed coating film was judged visually, and the surface having no streaks or unevenness on the surface and forming a uniform coating film was determined to be OK, and the surface having streaks or unevenness was determined to be NG.

(Flexibility)
Use a cylindrical mandrel with a diameter of 2 mm to check for cracks in the coating and / or peeling from the steel sheet when bent by a cylindrical mandrel, and comply with the flex resistance test of JIS K-5600-5-1. And evaluated. Those in which no cracking or peeling of the coating film occurred were regarded as acceptable.

(Copping resistance)
The presence or absence of cracking of the coating film and / or peeling from the steel sheet when subjected to partial deformation by indentation was evaluated using an indenter in accordance with the cupping resistance test of JIS K-5600-5-2. The indentation depth (mm) at which the coating film was cracked or peeled off by the indenter was defined as cupping resistance. The cupping resistance is a value indicating the substrate followability and flexibility of the coating film, and it can be said that the greater the numerical value of the indentation depth, the higher the followability and flexibility. The results are shown in Table 3.

(Weight resistance)
Use a weight of 10.3 mm in diameter and a weight of 1.0 kg to determine the presence or absence of cracking of the coating film and / or peeling from the steel sheet when it is deformed due to weight drop, and the resistance to JIS K-5600-5-3. Evaluation was made in accordance with a weight drop test. The lowest drop height at which cracking and peeling of the coating film occurred was defined as the weight drop resistance. The results are shown in Table 3.

(Cross cut tape peeling test)
The adhesion of the coating film was evaluated according to a cross-cut tape peeling test of JIS K-5600-8-5-2. The results are shown in Table 3. The numerical values in the table mean the number of squares that remained without being peeled in 100 squares.

(Measurement of coating film hardness)
The hardness of the coating film surface was measured in accordance with the scratch hardness test (pencil method) of JIS K-5600-5-4. The hardness of the hardest pencil with no scratch marks on the coating film surface was defined as the coating film hardness. did. The results are shown in Table 3.

(Weatherability)
The weather resistance of the coating film was evaluated based on the accelerated weather resistance test (ultraviolet fluorescent lamp method) of JIS K-5600-7-8 using a weather resistance test apparatus QUV (manufactured by Q-Panel). The cycle conditions were 1 cycle: UV irradiation at 70 ° C. for 8 hours and water vapor condensation at 50 ° C. for 4 hours, and this cycle was repeated. The surface gloss before and after the test (measured at an incident angle of 60 °) was measured with a haze / gloss reflectometer (manufactured by Big Gardner), and the gloss after the test was compared with the gloss before the test. evaluated. The results are shown in Table 3.

  From the results of Table 3, the coating films obtained in Examples 1 to 5 have sufficiently high mechanical strength, and the coating film appearance is better than the coating film obtained in Comparative Example 1. It was found that the pencil hardness was high and the weather resistance was excellent. From this, the two-pack type fluorine-containing coating composition of the present invention is excellent in solubility in an organic solvent having an aniline point of 70 ° C. or less, and the coating film formed using this has a good coating film appearance. It was confirmed that the weather resistance was sufficiently high.

  According to the present invention, it is possible to provide a two-pack type fluorinated coating composition capable of forming a coating film having a sufficiently good coating film appearance and sufficiently excellent weather resistance.

Claims (3)

A two-component fluorine-containing coating composition comprising a main agent containing a fluorine-containing polyol and a curing agent containing a polyisocyanate,
The main agent and / or the curing agent contains an organic solvent having an aniline point of 70 ° C. or lower, or an organic solvent having a mixed aniline point of 5 to 50 ° C.,
The fluorine-containing polyol is soluble in the organic solvent,
The polyisocyanate contains an aliphatic polyisocyanate obtained by reacting an aliphatic diisocyanate with a monoalcohol having 1 to 20 carbon atoms, and the molar ratio of allophanate groups and isocyanurate groups in the polyisocyanate is 100: 0. 90:10,
Two-component fluorine-containing coating composition.   The two-component fluorine-containing coating composition according to claim 1, wherein the aliphatic polyisocyanate is an aliphatic polyisocyanate obtained by reacting an aliphatic diisocyanate with a monoalcohol having 3 to 20 carbon atoms.   The two-component fluorine-containing coating composition according to claim 1 or 2, wherein the polyisocyanate has a viscosity at 25 ° C of 2000 mPa · s or less.