Curable composition and coating film

Abstract

To provide a curable composition that has low viscosity suitable for spray coating, resists separation of constituents during storage to ensure excellent storage stability, and produces a coating film with superior toughness and flame retardancy when cured.SOLUTION: A curable composition of the present invention comprises 100 pts.mass of a polymer having a hydrolyzable silyl group, 100-300 pts.mass of a hydrated metal compound not subjected to surface treatment, a thixotropic agent, and 40-150 pts.mass of a low-boiling liquid compound, wherein the composition has a viscosity of 1-30 Pa s at 100 rpm and 100-1000 Pa s at 1 rpm.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a curable composition and a coating film. [Background technology]

[0002] Conventionally, a coating film has been formed on the surface of an object to be coated in order to protect the object from impacts applied to the object and to impart flame retardancy to the object.

[0003] Patent Document 1 describes a BET specific surface area of ​​15 m 2 / g so that the ratio of the plasticizer oil absorption to the plasticizer content in a 55°C environment is 14% or more, and a polyvinyl chloride-based underbody coating composition having a specific gravity of 1.1 or less is disclosed.

[0004] Patent Document 2 discloses a flame-retardant moisture-curable adhesive composition containing, as essential components, (A) a reactive silicon group-containing organic polymer, (B) a metal hydroxide having an average particle size of 0.1 to 200 μm, and (C) a liquid compound having a viscosity of 500 mPa·s or less at 23°C, a dielectric constant of 5 or more, and / or a boiling point of 170°C or less. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-138887 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-064133 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the polyvinyl chloride-based underbody coating composition of Patent Document 1 has the problem that it requires heating for curing, which requires a large heating device.

[0007] The flame-retardant moisture-curable adhesive composition of Patent Document 2 differs from the polyvinyl chloride-based underbody coating compositions described above in that it does not require a heating step for curing, but it has the problem of producing a coating film with low toughness.

[0008] Furthermore, spray coating is often used to apply a coating material to a substrate. The flame-retardant moisture-curable adhesive composition described above cannot be spray-coated due to its high viscosity, and adding an organic solvent to reduce the viscosity causes separation of the components, resulting in another problem of poor storage stability.

[0009] The present invention provides a curable composition that has a low viscosity that allows application by spray coating, has excellent storage stability in that the components are less likely to separate even during storage, and is capable of producing a coating film (e.g., a coating film) that has excellent toughness and flame retardancy upon curing. [Means for solving the problem]

[0010] The curable composition of the present invention contains 100 parts by mass of a polymer having a hydrolyzable silyl group, 130 to 300 parts by mass of a surface-untreated hydrated metal compound, a thixotropic agent, and 40 to 150 parts by mass of a low-boiling-point liquid compound, and has a viscosity at 100 rpm of 1 to 30 Pa·s and a viscosity at 1 rpm of 100 to 1000 Pa·s.

[0011] [Polymers containing hydrolyzable silyl groups] The curable composition contains a polymer having a hydrolyzable silyl group. The polymer having a hydrolyzable silyl group is not particularly limited, and examples thereof include polyalkylene oxides having a hydrolyzable silyl group, acrylic polymers having a hydrolyzable silyl group, urethane polymers having a hydrolyzable silyl group, and polyolefin polymers having a hydrolyzable silyl group. The polymer having a hydrolyzable silyl group preferably contains a polyalkylene oxide having a hydrolyzable silyl group. The polymer having a hydrolyzable silyl group may be used alone or in combination of two or more.

[0012] The number average molecular weight of the polymer having a hydrolyzable silyl group is preferably 20,000 or more, more preferably 22,000 or more. The number average molecular weight of the polymer having a hydrolyzable silyl group is preferably 50,000 or less, more preferably 40,000 or less, more preferably 39,000 or less, and more preferably 30,000 or less. When the number average molecular weight of the polymer having a hydrolyzable silyl group is 20,000 or more, a coating film formed from the curable composition has excellent flame retardancy. When the number average molecular weight of the polymer having a hydrolyzable silyl group is 50,000 or less, the spray coating properties of the curable composition are improved, allowing it to be coated accurately to the desired location.

[0013] In the present invention, the number average molecular weight of the polymer having a hydrolyzable silyl group means a value calculated in terms of polystyrene measured by GPC (gel permeation chromatography).

[0014] The number average molecular weight of the polymer having a hydrolyzable silyl group can be measured, for example, using the following measuring device and under the following measuring conditions. Measuring device: TOSOH Corporation, product name "HLC-8121GPC / HT" Measurement conditions Column: TSKgelGMHHR-H(20)HT x 3 TSKguardcolumn-HHR(30)HT x 1 Mobile phase: o-DCB 1.0mL / min Sample concentration: 1 mg / mL Detector: Bryce type refractometer Standard material: Polystyrene (TOSOH Corporation, molecular weight: 500-8420000) Elution conditions: 145℃ SEC temperature: 145℃

[0015] [Polyalkylene oxide having hydrolyzable silyl groups] In the polyalkylene oxide having a hydrolyzable silyl group, the hydrolyzable silyl group is preferably an alkoxysilyl group, more preferably a dialkoxysilyl group, more preferably a dimethoxysilyl group, and more preferably a propyldimethoxysilyl group.

[0016] The polyalkylene oxide having a hydrolyzable silyl group preferably has an average of 1 to 4 hydrolyzable silyl groups per molecule. When the number of hydrolyzable silyl groups in the polyalkylene oxide having a hydrolyzable silyl group is within the above range, the flame retardancy of the coating film formed from the curable composition is improved. The polyalkylene oxide having a hydrolyzable silyl group preferably has a hydrolyzable silyl group at at least one of both ends of its main chain.

[0017] The average number of hydrolyzable silyl groups per molecule in the polyalkylene oxide having hydrolyzable silyl groups is 1 It can be calculated based on the concentration of hydrolyzable silyl groups in the polyalkylene oxide determined by H-NMR and the number average molecular weight of the polyalkylene oxide determined by GPC.

[0018] The polyalkylene oxide constituting the polyalkylene oxide having a hydrolyzable silyl group is a polyalkylene oxide having a main chain represented by the general formula (I): -(RO) m- (wherein R represents an alkylene group having 1 to 14 carbon atoms, and m represents the number of repeating units and is a positive integer.) The main chain skeleton of the polyalkylene oxide may be composed of only one type of repeating unit, or may be composed of two or more types of repeating units.

[0019] In the present invention, an alkylene group is a divalent atomic group formed by removing two hydrogen atoms bonded to two different carbon atoms in an aliphatic saturated hydrocarbon, and includes both linear and branched atomic groups.

[0020] Examples of the alkylene group include an ethylene group, a propylene group [-CH(CH3)-CH2-], a trimethylene group [-CH2-CH2-CH2-], a butylene group, an amylene group [-(CH2)5-], and a hexylene group.

[0021] Examples of the main chain skeleton of the polyalkylene oxide include polyethylene oxide, polypropylene oxide, polybutylene oxide, polytetramethylene oxide, polyethylene oxide-polypropylene oxide copolymer, and polypropylene oxide-polybutylene oxide copolymer. Among these, polypropylene oxide is preferred. Polypropylene oxide reduces the viscosity of the curable composition, improving spray coating properties and allowing the curable composition to be applied accurately to desired locations on the substrate.

[0022] The number average molecular weight of the polyalkylene oxide having a hydrolyzable silyl group is preferably 20,000 or more, more preferably 22,000 or more. The number average molecular weight of the polyalkylene oxide having a hydrolyzable silyl group is preferably 50,000 or less, more preferably 40,000 or less, and more preferably 39,000 or less. When the number average molecular weight of the polyalkylene oxide is 20,000 or more, the polyalkylene oxide does not easily thermally decompose into low molecular weight compounds, and therefore the coating film produced from the curable composition has excellent flame retardancy. When the number average molecular weight of the polyalkylene oxide is 50,000 or less, the spray coating properties of the curable composition are improved, allowing it to be applied to the desired location with precision.

[0023] In the present invention, the number average molecular weight of the polyalkylene oxide having a hydrolyzable silyl group means a value calculated in terms of polystyrene measured by GPC (gel permeation chromatography).

[0024] The number average molecular weight of the polyalkylene oxide having a hydrolyzable silyl group can be measured, for example, using the following measuring device and under the following measuring conditions. Measuring device: TOSOH Corporation, product name "HLC-8121GPC / HT" Measurement conditions Column: TSKgelGMHHR-H(20)HT x 3 TSKguardcolumn-HHR(30)HT x 1 Mobile phase: o-DCB 1.0mL / min Sample concentration: 1 mg / mL Detector: Bryce type refractometer Standard material: Polystyrene (TOSOH Corporation, molecular weight: 500-8420000) Elution conditions: 145℃ SEC temperature: 145℃

[0025] Commercially available polyalkylene oxides having a hydrolyzable silyl group can be used. For example, examples of polyalkylene oxides having a hydrolyzable silyl group include those manufactured by Kaneka Corporation under the trade names "MS Polymer S-203," "MS Polymer S-303," "MS Polymer S-303H," "Silyl Polymer SAT-200," "Silyl Polymer SAT-350," and "Silyl Polymer SAT-400." Examples of polyalkylene oxides having a hydrolyzable silyl group include those manufactured by Asahi Glass Company Limited under the trade names "Excestar ESS-3620," "Excestar ESS-2420," "Excestar ESS2410," and "Excestar ESS3430."

[0026] A polyalkylene oxide having a polypropylene oxide main chain and a (methoxymethyl)dimethoxysilyl group at the end of the polypropylene oxide is commercially available from Kaneka Corporation under the trade name "HS-2."

[0027] A polyalkylene oxide having a polypropylene oxide main chain and an isopropyldimethoxymethylsilyl group at the end of the polypropylene oxide is commercially available from Kaneka Corporation under the trade name "SAX720."

[0028] [Acrylic polymer having hydrolyzable silyl groups] As the hydrolyzable silyl group contained in the acrylic polymer having a hydrolyzable silyl group, an alkoxysilyl group is preferred, a trialkoxysilyl group is more preferred, and a trimethoxysilyl group is particularly preferred, because the hydrolysis reaction is mild.

[0029] In an acrylic polymer having a hydrolyzable silyl group, the average number of hydrolyzable silyl groups per molecule is preferably 1 or more, more preferably 2 or more. In an acrylic polymer having a hydrolyzable silyl group, the average number of hydrolyzable silyl groups per molecule is preferably 4 or less, more preferably 2.5 or less. When the number of hydrolyzable silyl groups is 1 or more, the flame retardancy of a coating film formed from the curable composition is improved. When the number of hydrolyzable silyl groups is 4 or less, the viscosity of the curable composition is reduced, improving spray coating properties, allowing the curable composition to be accurately applied to the desired location on the substrate. Furthermore, when the curable composition is applied to the coating location, the curable composition flows smoothly at the coating location, forming a coating film with a uniform thickness and imparting uniform flame retardancy to the entire substrate. The acrylic polymer having a hydrolyzable silyl group preferably has a hydrolyzable silyl group at at least one of the two terminals of its main chain.

[0030] An acrylic polymer having a hydrolyzable silyl group may be used in combination with an acrylic polymer not having a hydrolyzable silyl group. In this case, the total number of hydrolyzable silyl groups per molecule of both polymers is preferably 0.3 or more, more preferably 0.5 or more. When the number of hydrolyzable silyl groups is 0.3 or more, the curability of the curable composition is improved. On the other hand, the total number of hydrolyzable silyl groups per molecule of both polymers is preferably 2.0 or less, more preferably 1.8 or less. When the number of hydrolyzable silyl groups is 2.0 or less, the viscosity of the curable composition is reduced, improving spray coating properties, allowing the curable composition to be accurately applied to the desired coating location on the substrate. In addition, when the curable composition is applied to the coating location, the curable composition flows smoothly at the coating location, forming a coating film with a uniform thickness, and imparting uniform flame retardancy to the entire substrate.

[0031] The method for introducing a hydrolyzable silyl group into an acrylic polymer is not particularly limited, and examples thereof include a method in which an unsaturated group is introduced into a copolymer of monomers constituting the main chain skeleton, and then a hydrosilane having a hydrolyzable silyl group is allowed to react with the copolymer to hydrosilylate the copolymer.

[0032] The average number of hydrolyzable silyl groups per molecule in the acrylic polymer having hydrolyzable silyl groups is 1 It is calculated based on the concentration of hydrolyzable silyl groups in the acrylic polymer having hydrolyzable silyl groups determined by H-NMR and the number average molecular weight of the acrylic polymer having hydrolyzable silyl groups determined by GPC.

[0033] The main chain skeleton of the acrylic polymer having a hydrolyzable silyl group is preferably a copolymer of a monomer containing methyl (meth)acrylate and butyl (meth)acrylate, more preferably a copolymer of a monomer containing methyl methacrylate and butyl acrylate, and even more preferably a copolymer of a monomer containing methyl methacrylate and n-butyl acrylate. The acrylic polymer having a hydrolyzable silyl group, whose main chain skeleton is the copolymer, improves the flame retardancy of the coating film formed from the curable composition. Note that (meth)acrylate means methacrylate and / or acrylate.

[0034] In the acrylic polymer having a hydrolyzable silyl group, the content of the methyl (meth)acrylate component is preferably 3% by mass or more, more preferably 5% by mass or more. In the acrylic polymer having a hydrolyzable silyl group, the content of the methyl (meth)acrylate component is preferably 70% by mass or less, more preferably 50% by mass or less. When the content of the methyl (meth)acrylate component is 3% by mass or more, the viscosity of the curable composition is reduced, improving spray coating properties, allowing the curable composition to be applied accurately to the desired coating location on the substrate. Furthermore, when the curable composition is applied to the coating location, the curable composition flows smoothly at the coating location, forming a coating film with a uniform thickness, and imparting uniform flame retardancy to the entire substrate. When the content of the methyl (meth)acrylate component is 70% by mass or less, the viscosity of the curable composition is reduced, improving spray coating properties, allowing the curable composition to be applied accurately to the desired coating location on the substrate.

[0035] In the acrylic polymer having a hydrolyzable silyl group, the content of the butyl (meth)acrylate component is preferably 30 to 97 mass %, more preferably 50 to 95 mass %. When the content of the butyl (meth)acrylate component is 30 mass % or more, the viscosity of the curable composition is reduced, improving spray coating properties, and the curable composition can be applied with high precision to the desired coating location on the substrate.

[0036] In the acrylic polymer having a hydrolyzable silyl group, the monomers used in the polymer constituting the main chain skeleton may further include other monomers in addition to methyl acrylate, methyl methacrylate, butyl acrylate, and butyl methacrylate.Other monomers include, for example, styrene derivatives such as styrene, indene, α-methylstyrene, p-methylstyrene, p-chlorostyrene, p-chloromethylstyrene, p-methoxystyrene, p-tert-butoxystyrene, and divinylbenzene; compounds having a vinyl ester group such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caproate, vinyl benzoate, and vinyl cinnamate; maleic anhydride, N-vinylpyrrolidone, N-vinylmorpholine, methacrylonitrile, acrylonitrile, acrylamide, methacrylamide, N-cyclohexylmaleimide, N-phenylmaleimide, N-laurylmaleimide, N-benzylmaleimide, n-propyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, tert-butyl vinyl ether, tert-amyl vinyl ether, cyclohexyl vinyl ether, 2-ethylhexyl vinyl ether, dodecyl vinyl ether, octadecyl vinyl ether, 2-chloroethyl vinyl ether, ethylene glycol butyl vinyl ether, trimethylsilyl vinyl ether, methyl ... Examples of vinyloxy group-containing compounds include ethylene glycol methyl vinyl ether, (4-vinyloxy)butyl benzoate, ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, tetraethylene glycol divinyl ether, butane-1,4-diol divinyl ether, hexane-1,6-diol divinyl ether, cyclohexane-1,4-dimethanol divinyl ether, di(4-vinyloxy)butyl isophthalate, di(4-vinyloxy)butyl glutarate, di(4-vinyloxy)butyl succinate, trimethylolpropane trivinyl ether, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, 6-hydroxyhexyl vinyl ether, cyclohexane-1,4-dimethanol monovinyl ether, diethylene glycol monovinyl ether, 3-aminopropyl vinyl ether, 2-(N,N-diethylamino)ethyl vinyl ether, urethane vinyl ether, and polyester vinyl ether. These monomers may be used alone or in combination.

[0037] The polymerization method for the acrylic polymer having a hydrolyzable silyl group is not particularly limited, and known methods can be used. Examples of such polymerization methods include free radical polymerization, anionic polymerization, cationic polymerization, UV radical polymerization, living anionic polymerization, living cationic polymerization, and living radical polymerization.

[0038] The weight-average molecular weight of the acrylic polymer having a hydrolyzable silyl group is preferably 1000 to 50000, more preferably 2000 to 30000, and particularly preferably 3000 to 15000. An acrylic polymer having a hydrolyzable silyl group with a weight-average molecular weight within the above range reduces the viscosity of the curable composition, improving spray coatability and allowing the curable composition to be applied with high precision to desired coating locations on a substrate; and when the curable composition is applied to the coating locations, the curable composition flows smoothly at the coating locations to form a coating film with a uniform thickness, thereby imparting uniform flame retardancy to the entire substrate.

[0039] [Urethane polymer having hydrolyzable silyl groups] A urethane polymer refers to a polymer having a main chain formed by repeating urethane bonds (-NHCOO-). A urethane polymer having a hydrolyzable silyl group has a plurality of hydrolyzable silyl groups in the main chain of the urethane polymer. The urethane polymer having a hydrolyzable silyl group preferably has hydrolyzable silyl groups at both ends of the main chain of the urethane polymer.

[0040] [Polyolefin polymer having hydrolyzable silyl groups] Examples of polyolefin polymers include polyethylene polymers and polypropylene polymers. The polyolefin polymer having hydrolyzable silyl groups has a plurality of hydrolyzable silyl groups in the main chain of the polyolefin polymer. The polyolefin polymer having hydrolyzable silyl groups preferably has hydrolyzable silyl groups at both ends of the main chain of the polyolefin polymer.

[0041] [Untreated hydrated metal compounds] The curable composition contains a hydrated metal compound that has not been surface-treated. By including a hydrated metal compound that has not been surface-treated, the coating film produced from the curable composition can be imparted with excellent toughness and flame retardancy. In the present invention, "unsurface-treated" means that the entire surface is not covered with any other compound. A hydrated metal compound refers to a compound that contains a hydroxyl group (-OH) or water (HO) in the molecular form, and also contains a metal atom. Examples of metal atoms include Al, Mg, Ca, Zn, Si, Fe, Cu, Ba, Zr, Sn, Mg, Na, Al, Na, and B.

[0042] The non-surface-treated hydrated metal compound is not particularly limited as long as it has not been subjected to a surface treatment, and examples thereof include aluminum hydroxide [Al2O3·3H2O; or Al(OH)3], boehmite [Al2O3·H2O; or AlOOH], magnesium hydroxide [MgO·H2O; or Mg(OH)2], calcium hydroxide [CaO·H2O; or Ca(OH)2], zinc hydroxide [Zn(OH)2], silicic acid [H4SiO4; or H2SiO3; or H2Si2O5], iron hydroxide [Fe2O3·H2O or 2F Examples of suitable hydrated metal compounds include copper hydroxide [Cu(OH)2], barium hydroxide [BaO·H2O; or BaO·9H2O], zirconium oxide hydrate [ZrO·nH2O], tin oxide hydrate [SnO·H2O], basic magnesium carbonate [3MgCO3·Mg(OH)2·3H2O], hydrotalcite [6MgO·Al2O3·H2O], dawsonite [Na2CO3·Al2O3·nH2O], borax [Na2O·B2O5·5H2O], and zinc borate [2ZnO·3B2O5·3.5H2O]. The hydrated metal compounds listed above are not surface-treated. These untreated hydrated metal compounds may be used alone or in combination.

[0043] Since non-surface-treated hydrated metal compounds provide excellent flame retardancy and toughness to coating films produced from the curable composition, non-surface-treated aluminum hydroxide is preferred, and non-surface-treated aluminum hydroxide and non-surface-treated magnesium hydroxide are more preferred.

[0044] When the unsurface-treated hydrated metal compound contains unsurface-treated aluminum hydroxide and unsurface-treated magnesium hydroxide, the content ratio of the unsurface-treated aluminum hydroxide to the unsurface-treated magnesium hydroxide (mass of unsurface-treated aluminum hydroxide / mass of unsurface-treated magnesium hydroxide) is preferably 0.3 to 9, more preferably 0.5 to 6, and even more preferably 1 to 4. When the content ratio of the unsurface-treated aluminum hydroxide to the unsurface-treated magnesium hydroxide is 0.3 or more, the flame retardancy of the coating film formed from the curable composition is excellent. When the content ratio of the unsurface-treated aluminum hydroxide to the unsurface-treated magnesium hydroxide (mass of unsurface-treated aluminum hydroxide / mass of unsurface-treated magnesium hydroxide) is 9 or less, the toughness of the coating film formed from the curable composition is excellent.

[0045] The average particle size of the untreated hydrated metal compound is preferably 0.1 μm or more, more preferably 0.5 μm or more, and even more preferably 1 μm or more. The average particle size of the untreated hydrated metal compound is preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 1 μm or less. When the average particle size of the untreated hydrated metal compound is 0.1 μm or more, the untreated hydrated metal compound can be finely dispersed in the curable composition, thereby imparting excellent toughness to the coating film formed from the curable composition. When the average particle size of the untreated hydrated metal compound is 10 μm or less, the coating film formed from the curable composition can be imparted excellent toughness. Furthermore, the spray coatability of the curable composition is improved, allowing the curable composition to be applied accurately to the desired coating location on the substrate. Furthermore, when the curable composition is applied to the coating location, the curable composition flows smoothly at the coating location, forming a coating film with a uniform thickness, and imparting uniform flame retardancy to the entire substrate.

[0046] The average particle size of the unsurface-treated hydrated metal compound refers to the particle size D50 at which the cumulative frequency of particles from the smaller particle size side in the volume-based particle size distribution measured by laser diffraction method is 50 mass%.

[0047] The BET specific surface area of ​​untreated hydrated metal compounds is 3 m 2 / g or more is preferable, and 4m 2 / g or more is more preferable, and 5m 2 The BET specific surface area of ​​the untreated hydrated metal compound is preferably 10 m / g or more. 2 The BET specific surface area of ​​the untreated hydrated metal compound is preferably 3 m / g or less. 2 When the specific surface area of ​​the surface-treated hydrated metal compound is 10 m / g or more, the contact area with the polymer having a hydrolyzable silyl group increases, the separation of the components of the curable composition is reduced, and the storage stability of the curable composition is improved. 2 / g or less, the viscosity of the curable composition can be reduced, thereby improving the spray coatability of the curable composition. The BET specific surface area of ​​the unsurface-treated hydrated metal compound can be measured in accordance with JIS Z8830:2013 by a nitrogen adsorption method using a fully automatic specific surface area measuring device (for example, "Macsorb HM-1201" manufactured by Mountech Co., Ltd.).

[0048] The content of the non-surface-treated hydrated metal compound in the curable composition is 130 parts by mass or more, more preferably 150 parts by mass or more, and more preferably 180 parts by mass or more, per 100 parts by mass of the polymer having a hydrolyzable silyl group. The content of the hydrated metal compound in the curable composition is preferably 300 parts by mass or less, more preferably 280 parts by mass or less, and more preferably 250 parts by mass or less, per 100 parts by mass of the polymer having a hydrolyzable silyl group. When the content of the non-surface-treated hydrated metal compound is 130 parts by mass or more, the toughness of the coating film formed from the curable composition is improved. When the content of the non-surface-treated hydrated metal compound is 300 parts by mass or less, the toughness of the coating film formed from the curable composition is improved. Furthermore, the spray coatability of the curable composition is improved, allowing the curable composition to be applied with high precision to the desired coating location on the substrate; and when the curable composition is applied to the coating location, the curable composition flows smoothly at the coating location, forming a coating film with a uniform thickness and imparting uniform flame retardancy to the entire substrate.

[0049] [Thixotropic Agents] The curable composition contains a thixotropic agent, which prevents aggregation and precipitation of the non-surface-treated hydrated metal compound in the curable composition, improves dispersibility, and imparts excellent storage stability to the curable composition. Furthermore, the curable composition also imparts excellent flame retardancy to the coating film formed from the curable composition.

[0050] The thixotropic agent is preferably an organic thixotropic agent. The term "organic thixotropic agent" refers to a thixotropic agent that contains at least one carbon atom (preferably two or more) and a carbon-hydrogen bond (C—H bond) in the molecule.

[0051] The organic thixotropic agent is not particularly limited, and examples thereof include fatty acid amides (amide wax type) synthesized from vegetable oil fatty acid and amine; surfactants such as fatty acid esters, polyethers, sulfated oils, and higher alcohol sulfates; polycarboxylic acid esters; polycarboxylic acid amides; urea-modified compounds, etc., and fatty acid amides (amide wax type) synthesized from vegetable oil fatty acid and amine are preferred. The thixotropic agent may be used alone or in combination of two or more.

[0052] The content of the thixotropic agent in the curable composition is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more, per 100 parts by mass of the polymer having a hydrolyzable silyl group. The content of the thixotropic agent in the curable composition is preferably 5 parts by mass or less, more preferably 4 parts by mass or less, and more preferably 3 parts by mass or less, per 100 parts by mass of the polymer having a hydrolyzable silyl group. When the content of the thixotropic agent is 0.1 parts by mass or more, the storage stability of the curable composition is improved, and the flame retardancy of the coating film formed from the curable composition is improved. When the content of the thixotropic agent is 5 parts by mass or less, the spray coatability of the curable composition is improved.

[0053] [Low boiling point liquid compounds] The curable composition contains a low-boiling-point liquid compound. The low-boiling-point liquid compound is liquid at 20°C and 1 atmosphere (0.101 MPa). The term "liquid" refers to a state in which the compound does not have a fixed shape, is fluid, and has a substantially fixed volume.

[0054] By including a low-boiling point liquid compound in the curable composition, the viscosity of the curable composition is reduced, improving spray coating properties, allowing the curable composition to be applied with high precision to the desired coating location on the substrate; and when the curable composition is applied to the coating location, the curable composition flows smoothly at the coating location, forming a coating film with a uniform thickness and imparting uniform flame retardancy to the entire substrate.

[0055] The low-boiling point liquid compound is not particularly limited, and examples thereof include aromatic hydrocarbon solvents such as toluene, xylene, and ethylbenzene, ester solvents such as ethyl acetate and butyl acetate, ketone solvents such as acetone and methyl ethyl ketone, alcohols such as methanol, ethanol, isopropyl alcohol, and normal propyl alcohol, and halides thereof, with alcohols or halides thereof being preferred because they have excellent compatibility with polymers having hydrolyzable silyl groups, reduce separation of the components of the curable composition, and improve the storage stability of the curable composition. The low-boiling point liquid compound may be used alone or in combination of two or more.

[0056] The content of the low-boiling point liquid compound in the curable composition is 40 parts by mass or more, preferably 45 parts by mass or more, and more preferably 50 parts by mass or more, per 100 parts by mass of the polymer having a hydrolyzable silyl group. The content of the low-boiling point liquid compound in the curable composition is 150 parts by mass or less, preferably 130 parts by mass or less, more preferably 120 parts by mass or less, and more preferably 110 parts by mass or less, per 100 parts by mass of the polymer having a hydrolyzable silyl group. When the content of the low-boiling point liquid compound is 40 parts by mass or more, the viscosity of the curable composition is reduced, improving spray coating properties and forming a coating film with uniform flame retardancy. When the content of the low-boiling point liquid compound is 150 parts by mass or less, the storage stability of the curable composition is improved.

[0057] [Phosphoric acid condensate] The curable composition preferably contains a phosphoric acid condensate, which can impart excellent flame retardancy to a coating film formed from the curable composition.

[0058] The curable composition contains a non-surface-treated hydrated metal compound and a phosphoric acid condensate, and also contains a thixotropic agent and a low-boiling-point liquid compound, thereby suppressing separation of the non-surface-treated hydrated metal compound and the phosphoric acid condensate during storage, resulting in excellent storage stability. Furthermore, by using a combination of a non-surface-treated hydrated metal compound and a phosphoric acid condensate, both the non-surface-treated hydrated metal compound and the phosphoric acid condensate can be stably finely dispersed in the curable composition. Therefore, the viscosity of the curable composition is reduced, improving spray coating properties, allowing the curable composition to be accurately applied to the desired coating location on the substrate. Furthermore, when the curable composition is applied to the coating location, the curable composition flows smoothly at the coating location, forming a coating film with a uniform thickness, and imparting uniform flame retardancy to the entire resulting coating film.

[0059] The phosphoric acid condensate is not particularly limited, but a condensed phosphoric acid ester is preferred. The phosphoric acid condensates may be used alone or in combination of two or more.

[0060] The condensed phosphate ester is a phosphate ester having multiple phosphorus atoms in the molecule. The condensed phosphate ester is not particularly limited, and examples thereof include aromatic condensed phosphate esters such as trialkyl polyphosphate, resorcinol polyphenyl phosphate, bisphenol A polycresyl phosphate, and bisphenol A polyphenyl phosphate.

[0061] Phosphate esters have excellent affinity with untreated surface-treated hydrated metal compounds, reduce the viscosity of the curable composition, improve spray coating properties, and enable the curable composition to be applied accurately to a narrow desired coating location. For this reason, trimethyl phosphate, triethyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, resorcinol polyphenyl phosphate, bisphenol A polycresyl phosphate, and bisphenol A bisdiphenyl phosphate [formula (V)] are preferred, and trigresyl phosphate, resorcinol polyphenyl phosphate [formula (II)], cresyl di-2,6-xylenyl phosphate [formula (III)], tris(chloropropyl) phosphate [formula (IV)], bisphenol A polycresyl phosphate, and bisphenol A bisdiphenyl phosphate [formula (V)] are more preferred.

[0062] [ka]

[0063] [ka]

[0064] [ka]

[0065] [ka]

[0066] The phosphoric acid condensate is preferably in a liquid state at 20° C. and 1 atmosphere (0.101 MPa). The term "liquid" refers to a state in which the phosphoric acid condensate does not have a fixed shape, is fluid, and has a substantially fixed volume.

[0067] The fluidity of the phosphoric acid condensate improves the dispersibility of the non-surface-treated hydrated metal compound in the curable composition, and the non-surface-treated hydrated metal compound is uniformly dispersed in the curable composition together with the non-surface-treated hydrated metal compound. This allows the non-surface-treated hydrated metal compound and the phosphoric acid condensate to be uniformly dispersed in the coating film produced from the curable composition, thereby forming a coating film with excellent flame retardancy.

[0068] The content of the phosphoric acid condensate in the curable composition is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, more preferably 15 parts by mass or more, more preferably 20 parts by mass or more, and more preferably 25 parts by mass or more, per 100 parts by mass of the polymer having a hydrolyzable silyl group. The content of the phosphoric acid condensate in the curable composition is preferably 50 parts by mass or less, more preferably 45 parts by mass or less, more preferably 40 parts by mass or less, and more preferably 35 parts by mass or less, per 100 parts by mass of the polymer having a hydrolyzable silyl group. When the content of the phosphoric acid condensate is 5 parts by mass or more, it is possible to impart excellent flame retardancy to a coating film formed from the curable composition and to impart excellent storage stability to the curable composition. When the content of the phosphoric acid condensate is 50 parts by mass or less, the curable composition can form a coating film having excellent flame retardancy.

[0069] In the curable composition, the content ratio of the non-surface-treated hydrated metal compound to the phosphoric acid condensate (mass of the non-surface-treated hydrated metal compound / mass of the phosphoric acid condensate) is preferably 2 or more, more preferably 3 or more, and even more preferably 4 or more. In the curable composition, the content ratio of the non-surface-treated hydrated metal compound to the phosphoric acid condensate (mass of the non-surface-treated hydrated metal compound / mass of the phosphoric acid condensate) is preferably 15 or less, more preferably 13 or less, more preferably 10 or less, and even more preferably 8 or less. When the content ratio of the non-surface-treated hydrated metal compound to the phosphoric acid condensate (mass of the non-surface-treated hydrated metal compound / mass of the phosphoric acid condensate) is within the above range, the storage stability and spray coatability of the curable composition can be improved, and the flame retardancy of the coating film formed from the curable composition can be improved.

[0070] When the phosphoric acid condensate is liquid, the viscosity of the phosphoric acid condensate at 40°C is preferably 3000 mPa·s or less, more preferably 2800 mPa·s or less, and even more preferably 2500 mPa·s or less. When the phosphoric acid condensate is liquid, the viscosity of the phosphoric acid condensate at 40°C is preferably 500 mPa·s or more, and more preferably 1000 mPa·s or more. When the viscosity of the phosphoric acid condensate at 40°C is 3000 mPa·s or less, the storage stability and spray coatability of the curable composition can be improved. When the viscosity of the phosphoric acid condensate at 40°C is 3000 mPa·s or less, the flame retardancy of the coating film formed from the curable composition can be improved. The viscosity of the phosphoric acid condensate is a value measured using a Brookfield type B viscometer specified in JIS K7117.

[0071] [Surface-treated filler] The curable composition may contain a surface-treated filler. By containing the surface-treated filler, the storage stability of the curable composition is improved. The filler does not contain a hydrated metal compound. It is preferable that the filler does not contain water (HO) and a hydroxyl group (—OH) in the molecular form.

[0072] The filler is not particularly limited as long as a part or the whole of its surface is treated and coated with another compound, and examples thereof include calcium carbonate, magnesium carbonate, calcium oxide, silicic anhydride, finely powdered silica, calcium silicate, titanium dioxide, clay, talc, carbon black, and glass balloons. The filler may be used alone or in combination of two or more. Calcium carbonate is preferred as the filler.

[0073] The average particle size of the filler is preferably 0.01 μm or more, more preferably 0.02 μm or more. The average particle size of the filler is preferably 10 μm or less, more preferably 5 μm or less, more preferably 4 μm or less, more preferably 3 μm or less, more preferably 2 μm or less, and more preferably 1 μm or less. When the average particle size of the filler is 0.01 μm or more, the spray coating properties of the curable composition are improved. When the average particle size of the filler is 10 μm or less, the storage stability of the curable composition is improved.

[0074] The average particle size of the filler is a value calculated based on the following formula using the specific gravity of the filler and the specific surface area per gram of filler. The specific surface area per gram of filler can be measured in accordance with JIS Z8830 (2013). The specific surface area per gram of filler can be measured using, for example, a powder specific surface area measuring device commercially available from Shimadzu Corporation under the product name "SS-100 Model." Average particle size of filler (C) (μm) =6×10000 / (specific gravity×specific surface area)

[0075] The filler is preferably surface-treated with a surface treatment agent such as a fatty acid, a fatty acid ester, or a fatty acid metal salt. The surface treatment agents may be used alone or in combination of two or more.

[0076] Examples of fatty acids include caproic acid, caprylic acid, pelargonic acid, capric acid, undecanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, alaic acid, behenic acid, lignoceric acid, cerotic acid, montanic acid, melissic acid, obscylic acid, caroleic acid, undecylenic acid, linderic acid, tsuzuic acid, physeteric acid, moristoic acid, palmitoleic acid, petroselinic acid, oleic acid, elaidic acid, asclevic acid, vaccenic acid, gadoleic acid, gondoic acid, cetoleic acid, erucic acid, brassidic acid, selacholeic acid, ximenic acid, lumecic acid, sorbic acid, and linoleic acid. Of these, lauric acid, myristic acid, palmitic acid, stearic acid, and oleic acid are preferred.

[0077] Examples of fatty acid esters include stearyl stearate, lauryl stearate, stearyl palmitate, and lauryl palmitate.

[0078] Examples of fatty acid metal salts include sodium salts and potassium salts of the above fatty acids, and preferred are sodium salts of lauric acid, sodium salts of myristic acid, sodium salts of palmitic acid, sodium salts of stearic acid and sodium salts of oleic acid.

[0079] The content of the surface-treated filler in the curable composition is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and more preferably 15 parts by mass or more, per 100 parts by mass of the polymer having a hydrolyzable silyl group. The content of the surface-treated filler in the curable composition is preferably 100 parts by mass or less, more preferably 90 parts by mass or less, more preferably 80 parts by mass or less, more preferably 70 parts by mass or less, more preferably 60 parts by mass or less, more preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and more preferably 30 parts by mass or less, per 100 parts by mass of the polymer having a hydrolyzable silyl group. When the content of the surface-treated filler is 5 parts by mass or more, the storage stability of the curable composition is improved. When the content of the surface-treated filler is 100 parts by mass or less, the spray coatability of the curable composition is improved, and the flame retardancy of the coating film formed from the curable composition is improved.

[0080] [Silanol condensation catalyst] The curable composition may contain a silanol condensation catalyst, which is a catalyst for promoting a dehydration condensation reaction between silanol groups formed by hydrolysis of hydrolyzable silyl groups contained in the curable composition.

[0081] Examples of silanol condensation catalysts include dibutyltin diacetylacetonate, 1,1,3,3-tetrabutyl-1,3-dilauryloxycarbonyl-distannoxane, dibutyltin dilaurate, dibutyltin oxide, dibutyltin diacetate, dibutyltin phthalate, bis(dibutyltin laurate) oxide, dibutyltin bis(acetylacetonate), dibutyltin bis(monoester maleate), tin octoate, dibutyltin octoate, dioctyltin oxide, dibutyltin bis(triethoxysilicate), bis(dibutyltin bistriethoxysilicate) oxide, and dibutyltin oxybisethoxysilicate and other organic tin compounds; tetra-n-butoxy titanate, and tetraisopropoxy titanate and other organic titanium compounds, and organic tin compounds are preferred.These silanol condensation catalysts may be used alone or in combination of two or more.

[0082] The silanol condensation catalyst is preferably 1,1,3,3-tetrabutyl-1,3-dilauryloxycarbonyl-distannoxane, which makes it possible to easily adjust the curing rate of the curable composition.

[0083] The content of the silanol condensation catalyst in the curable composition is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, and more preferably 0.3 parts by mass or more, per 100 parts by mass of the polymer having a hydrolyzable silyl group. The content of the silanol condensation catalyst in the curable composition is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, more preferably 6 parts by mass or less, and more preferably 5 parts by mass or less, per 100 parts by mass of the polymer having a hydrolyzable silyl group. When the content of the silanol condensation catalyst in the curable composition is 0.1 parts by mass or more, the curing rate of the curable composition can be increased, and the time required for curing the curable composition can be shortened. When the content of the silanol condensation catalyst in the curable composition is 10 parts by mass or less, the curable composition has an appropriate curing rate, and the storage stability and handleability of the curable composition can be improved.

[0084] [Dehydrating agent] The curable composition preferably further contains a dehydrating agent, which can prevent the curable composition from being cured by moisture contained in the air or the like during storage.

[0085] Examples of dehydrating agents include silane compounds such as vinyltrimethoxysilane, dimethyldimethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, tetramethoxysilane, phenyltrimethoxysilane, and diphenyldimethoxysilane; and ester compounds such as methyl orthoformate, ethyl orthoformate, methyl orthoacetate, and ethyl orthoacetate. These dehydrating agents may be used alone or in combination. Among them, vinyltrimethoxysilane is preferred.

[0086] The content of the dehydrating agent in the curable composition is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, per 100 parts by mass of the polymer having a hydrolyzable silyl group. The content of the dehydrating agent in the curable composition is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, per 100 parts by mass of the polymer having a hydrolyzable silyl group. When the content of the dehydrating agent in the curable composition is 0.5 parts by mass or more, the effects obtained by the dehydrating agent are sufficiently obtained. Furthermore, when the content of the dehydrating agent in the curable composition is 20 parts by mass or less, the curable composition has excellent curability.

[0087] [Other additives] The curable composition may contain other additives such as an adhesion promoter, a thixotropy promoter, an antioxidant, an ultraviolet absorber, a pigment, a dye, an anti-settling agent, an aminosilane coupling agent, and a plasticizer, within the range that does not impair the physical properties of the curable composition. Of these, the adhesion promoter, the thixotropy promoter, the ultraviolet absorber, and the antioxidant are preferred.

[0088] The curable composition preferably contains an adhesion promoter. The use of an adhesion promoter can improve the adhesion of the curable composition to the substrate. Examples of adhesion promoters include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethylmethyldiethoxysilane, 3-glycidoxypropyltrimethethoxysilane, 2-aminoethyl-3-aminopropylmethyldimethoxysilane, 2-aminoethyl-3-aminopropyltrimethoxysilane, and 2-aminoethyl-3-aminopropyltriethoxysilane. 3-glycidoxypropyltrimethoxysilane and 2-aminoethyl-3-aminopropyltrimethoxysilane are preferred. The adhesion promoters may be used alone or in combination of two or more.

[0089] The content of the adhesion promoter in the curable composition is preferably 1 to 10 parts by mass, more preferably 1 to 5 parts by mass, per 100 parts by mass of the polymer having a hydrolyzable silyl group. When the content of the aminosilane coupling agent is within the above range, the rubber elasticity and adhesiveness of the cured product of the curable composition can be improved.

[0090] The curable composition preferably contains an aminosilane coupling agent. By using the aminosilane coupling agent, the rubber elasticity and adhesiveness of the coating film formed from the curable composition can be improved. The aminosilane coupling agent refers to a compound containing a silicon atom to which an alkoxy group is bonded and a functional group containing a nitrogen atom in one molecule.

[0091] Examples of aminosilane coupling agents include 3-aminopropyltrimethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, N,N'-bis-[3-(trimethoxysilyl)propyl]ethylenediamine, N,N'-bis-[3-(triethoxysilyl)propyl]ethylenediamine, N,N'-bis-[3-(methyldimethoxysilyl)propyl]ethylenediamine, N,N'-bis-[3-(trimethoxysilyl)propyl]hexamethylenediamine, and N,N'-bis-[3-(triethoxysilyl)propyl]hexamethylenediamine. These aminosilane coupling agents may be used alone or in combination of two or more.

[0092] Among these, preferred examples of the aminosilane coupling agent include 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, and N-(2-aminoethyl)-3-aminopropyltriethoxysilane, and more preferred example is N-(2-aminoethyl)-3-aminopropyltrimethoxysilane.

[0093] The content of the aminosilane coupling agent in the curable composition is preferably 1 to 10 parts by mass, more preferably 1 to 5 parts by mass, per 100 parts by mass of the polymer having a hydrolyzable silyl group. When the content of the aminosilane coupling agent is within the above range, the rubber elasticity and adhesiveness of the cured product of the curable composition can be improved.

[0094] The thixotropy-imparting agent may be any agent capable of imparting thixotropy to the curable composition, and preferred examples of the thixotropy-imparting agent include hydrogenated castor oil, fatty acid bisamide, and fumed silica.

[0095] The content of the thixotropy-imparting agent in the curable composition is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, per 100 parts by mass of the polymer having a hydrolyzable silyl group. The content of the thixotropy-imparting agent in the curable composition is preferably 200 parts by mass or less, more preferably 150 parts by mass or less, per 100 parts by mass of the polymer having a hydrolyzable silyl group. When the content of the thixotropy-imparting agent in the curable composition is 0.1 parts by mass or more, thixotropy can be effectively imparted to the curable composition. Furthermore, when the content of the thixotropy-imparting agent in the curable composition is 200 parts by mass or less, the curable composition has an appropriate viscosity, improving the handleability of the curable composition.

[0096] Examples of the ultraviolet absorber include benzotriazole-based ultraviolet absorbers and benzophenone-based ultraviolet absorbers, with benzotriazole-based ultraviolet absorbers being preferred. The content of the ultraviolet absorber in the curable composition is preferably 0.1 parts by mass or more relative to 100 parts by mass of the polymer having a hydrolyzable silyl group. The content of the ultraviolet absorber in the curable composition is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, relative to 100 parts by mass of the polymer having a hydrolyzable silyl group.

[0097] Examples of antioxidants include hindered phenol antioxidants, monophenol antioxidants, bisphenol antioxidants, and polyphenol antioxidants, with hindered phenol antioxidants being preferred. The content of the antioxidant in the curable composition is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, per 100 parts by mass of the polymer having a hydrolyzable silyl group. The content of the antioxidant in the curable composition is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, per 100 parts by mass of the polymer having a hydrolyzable silyl group.

[0098] [Light stabilizer] The curable composition preferably contains a hindered amine light stabilizer, which can provide a curable composition that can maintain excellent rubber elasticity for a longer period of time in the coating film produced by curing.

[0099] Examples of hindered amine light stabilizers include a mixture of bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate, bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, dibutylamine·1,3,5-triazine·N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine) and N-(2,2,6,6 poly[{6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl}{(2,2,6,6-tetramethyl-4-piperidyl)imino}hexamethylene{(2,2,6,6-tetramethyl-4-piperidyl)imino}], and a polycondensate of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol.

[0100] Preferred examples of the hindered amine light stabilizer include NOR-type hindered amine light stabilizers, which can provide a curable composition that is inhibited from decreasing in rubber elasticity over time after curing.

[0101] The NOR hindered amine light stabilizer has a NOR structure in which an alkyl group (R) is bonded to a nitrogen atom (N) contained in a piperidine ring skeleton via an oxygen atom (O). The number of carbon atoms in the alkyl group in the NOR structure is preferably 1 to 20, more preferably 1 to 18, and particularly preferably 18. Examples of the alkyl group include a linear alkyl group, a branched alkyl group, and a cyclic alkyl group (a saturated alicyclic hydrocarbon group).

[0102] Examples of linear alkyl groups include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-octyl, n-nonyl, and n-decyl groups. Examples of branched alkyl groups include isopropyl, isobutyl, sec-butyl, and tert-butyl. Examples of cyclic alkyl groups (saturated alicyclic hydrocarbon groups) include cyclopentyl, cyclohexyl, and cyclooctyl groups. In addition, the hydrogen atoms constituting the alkyl group may be substituted with halogen atoms (e.g., fluorine, chlorine, and bromine atoms) or hydroxyl groups.

[0103] Examples of the NOR type hindered amine light stabilizer include hindered amine light stabilizers represented by the following formula (I).

[0104] [ka]

[0105] When a NOR type hindered amine light stabilizer is used, it is preferable to use the NOR type hindered amine light stabilizer in combination with a benzotriazole type UV absorber or a triazine type UV absorber, which can provide a curable composition in which the coating film produced by curing exhibits less deterioration in rubber elasticity over time.

[0106] The content of the hindered amine light stabilizer in the curable composition is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, relative to 100 parts by mass of the polymer having a hydrolyzable silyl group, and is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, relative to 100 parts by mass of the polymer having a hydrolyzable silyl group.

[0107] [Curable composition] The curable composition can be produced by mixing a polymer having a hydrolyzable silyl group, a non-surface-treated hydrated metal compound, a thixotropic agent, a low-boiling point liquid compound, and additives that are added as needed.

[0108] As described above, the curable composition contains a combination of the constituent components, and thus has low viscosity and excellent storage stability.

[0109] The viscosity of the curable composition at 100 rpm at 23°C (100 rpm viscosity) is 1 Pa·s or more, preferably 2 Pa·s or more, and more preferably 3 Pa·s or more. The viscosity at 100 rpm at 23°C (100 rpm viscosity) is 30 Pa·s or less, preferably 25 Pa·s or less, and more preferably 20 Pa·s or less. When the 100 rpm viscosity at 23°C is 1 Pa·s or more, the fine dispersion of the non-surface-treated hydrated metal compound can be stably maintained, improving the storage stability of the curable composition. Furthermore, the non-surface-treated hydrated metal compound can be uniformly dispersed in a coating film formed from the curable composition, imparting uniformity and excellent flame retardancy. When the 100 rpm viscosity at 23°C is 30 Pa·s or less, the spray applicability of the curable composition is improved, allowing the curable composition to be applied accurately to the desired location on the substrate, and easily forming a coating film with excellent flame retardancy and toughness on the substrate. The 100 rpm viscosity of the curable composition refers to a value measured using a Brookfield viscometer under conditions of 23° C., 100 rpm, and rotor No. 7 in accordance with JIS K6833.

[0110] The viscosity of the curable composition at 1 rpm at 23°C (1 rpm viscosity) is 100 Pa·s or more, preferably 150 Pa·s or more, and more preferably 200 Pa·s or more. The viscosity at 1 rpm at 23°C (1 rpm viscosity) is 1000 Pa·s or less, preferably 800 Pa·s or less, more preferably 600 Pa·s or less, more preferably 400 Pa·s or less, and more preferably 300 Pa·s or less. When the 1 rpm viscosity at 23°C is 100 Pa·s or more, the fine dispersion of the non-surface-treated hydrated metal compound can be stably maintained, improving the storage stability of the curable composition. In addition, the non-surface-treated hydrated metal compound can be uniformly dispersed in a coating film formed from the curable composition, imparting uniform and excellent flame retardancy. When the 1 rpm viscosity at 23°C is 1000 Pa s or less, the spray coatability of the curable composition is improved, the curable composition can be applied accurately to the desired location on the substrate, and a coating film with excellent flame retardancy and toughness can be easily formed on the substrate. The 1 rpm viscosity of the curable composition is the value measured using a B-type viscometer in accordance with JIS K6833 under conditions of 23°C, 1 rpm, and rotor No. 4.

[0111] The curable composition uses a polymer having a hydrolyzable silyl group as a base resin and contains a combination of an unsurface-treated hydrated metal compound, a thixotropic agent, and a low-boiling-point liquid compound, thereby stably ensuring excellent fine dispersion of the unsurface-treated hydrated metal compound in the curable composition and achieving a low viscosity of the curable composition. This allows for the production of a coating film that has excellent spray coating properties, a uniform film thickness, and overall homogeneous flame retardancy. The curable composition has excellent storage stability because the unsurface-treated hydrated metal compound is stably finely dispersed. The coating film produced by curing the curable composition has the unsurface-treated hydrated metal compound finely dispersed without agglomeration, and therefore has excellent flame retardancy and toughness.

[0112] The curable composition, particularly when further containing a phosphoric acid condensate, exhibits excellent storage stability by further suppressing separation of the untreated hydrated metal compound and the phosphoric acid condensate during storage. Furthermore, both the untreated hydrated metal compound and the phosphoric acid condensate can be more stably finely dispersed in the curable composition. This reduces the viscosity of the curable composition, further improving spray coating properties, forming a coating film with a uniform thickness, and imparting uniform flame retardancy to the entire resulting coating film.

[0113] The curable composition can be spray-coated with high precision at predetermined locations on a substrate without affecting the performance of the substrate. The coating film produced by curing the curable composition can impart or improve the flame retardancy of the substrate, and the toughness of the coating film can protect the substrate from impact forces applied to it.

[0114] Furthermore, the coating film formed by curing the curable composition has excellent toughness (impact resistance). The curable composition is spray-coated onto a substrate that requires impact resistance, and a coating film with excellent impact resistance can be easily formed on the surface of the substrate. Even when an impact force is applied to the substrate, the coating film formed from the curable composition does not suffer damage such as cracking, and can stably maintain the excellent flame retardancy imparted to the substrate.

[0115] The substrate to be coated is not particularly limited, and examples thereof include vehicles such as automobiles, ships, aircraft, electronic devices, electronic materials, and storage containers (synthetic resin containers, metal containers, etc.).

[0116] When the curable composition is applied to a vehicle as the substrate, it is preferable to use the curable composition to form a coating film on the bottom of the vehicle body, which is the part of the vehicle that is likely to be subjected to impact forces such as collisions with stones while the vehicle is running.

[0117] Examples of electronic devices include, but are not limited to, car navigation systems, mobile phones, smartphones, game consoles, digital cameras, televisions, DVD players, electronic dictionaries, calculators, hard disk recorders, personal computers, video cameras, printers, liquid crystal displays, plasma displays, radios, and electronic musical instruments.

[0118] As electronic devices are becoming smaller and lighter, the electronic materials that make up the devices are also becoming smaller. Examples of such electronic materials include, but are not limited to, printed wiring boards, light-emitting diodes (LEDs), light-emitting diode-mounted boards, flexible copper-clad laminates, bonding sheets, touch panels, and sensor substrates.

[0119] The storage container is not particularly limited, but examples thereof include containers for storing flammable liquids (for example, organic solvents, organic compounds, gasoline, diesel, kerosene, etc.).

[0120] The method for applying the curable composition to a predetermined coating location on the substrate is not particularly limited, and examples thereof include spray coating, a coating method using a brush, and a coating method using a known coating tool. However, as described above, the curable composition has a low viscosity, so spray coating can be preferably used.

[0121] The curable composition applied to the substrate produces a cured product by curing the polymer having a hydrolyzable silyl group. The curing of the polymer having a hydrolyzable silyl group may be carried out in a known manner (e.g., by supplying moisture, irradiating with light such as ultraviolet light, heating, etc.) depending on the type of polymer having a hydrolyzable silyl group.

[0122] Furthermore, the coating film produced by curing the curable composition has excellent toughness and flame retardancy, and even when an impact force is applied, the occurrence of damage such as cracks is generally suppressed, protecting the coated object from impact and exhibiting excellent flame retardancy even in the event of a fire. [Effects of the Invention]

[0123] The curable composition of the present invention has a low viscosity that allows it to be applied by spray coating, and has excellent storage stability as the components are less likely to separate even during storage. Furthermore, upon curing, it can produce a coating film (e.g., a coating film) that has excellent toughness and flame retardancy.

[0124] The coating film produced by curing the curable composition has excellent flame retardancy and toughness, and can impart excellent flame retardancy to the coated object or improve the flame retardancy, while also protecting the coated object from impact forces. DETAILED DESCRIPTION OF THE INVENTION

[0125] The present invention will be described in more detail below using examples, but the present invention is not limited to these examples. [Example]

[0126] The following raw materials were used in producing the curable compositions of the Examples and Comparative Examples.

[0127] [Polymers containing hydrolyzable silyl groups] Polyalkylene oxide having a hydrolyzable silyl group (polymer 1 having a hydrolyzable silyl group, polyalkylene oxide having a main chain skeleton made of polypropylene oxide and a dimethoxysilyl group at the end of the main chain, number average molecular weight: 38,000, manufactured by Kaneka Corporation, product name "Excestar S303H") Polyalkylene oxide having a hydrolyzable silyl group (polymer 2 having a hydrolyzable silyl group, polyalkylene oxide having a main chain skeleton made of polypropylene oxide and a trimethoxysilyl group at the end of the main chain via a urethane bond, number average molecular weight: 35,000)

[0128] [Untreated hydrated metal compounds] Non-surface-treated aluminum hydroxide (non-surface-treated aluminum hydroxide, manufactured by DAEJOO KC Co., Ltd., product name "KH101"), average particle size: 1 μm, BET specific surface area: 7 m 2 / g)

[0129] [Surface-treated hydrated metal compounds] Surface-treated aluminum hydroxide (surface-treated aluminum hydroxide, manufactured by Nippon Light Metal Co., Ltd., product name "BSP", average particle size: 1 μm, BET specific surface area: 7 m 2 / g, surface treatment: surface treatment with fatty acid)

[0130] [Thixotropic Agents] Amide wax (manufactured by Ito Oil Co., Ltd., product name "T1800")

[0131] [Low boiling point liquid compounds] Ethyl alcohol [liquid at 20°C and 1 atmosphere (0.101 MPa)]

[0132] [Phosphoric acid condensate] Bisphenol A bisdiphenyl phosphate (condensed phosphate ester, manufactured by Daihachi Chemical Industry Co., Ltd., trade name "CR-741", viscosity at 40°C: 2300 mPa·s)

[0133] [Non-phosphoric acid condensation product] Polyether polyol (AGC product name "E3020")

[0134] [Filling material] Surface-treated calcium carbonate (surface-treated calcium carbonate, does not contain water (H2O) in molecular form, product name "PLS505" manufactured by Konoshima Chemical Co., Ltd., surface treatment: surface treatment with fatty acid, average particle size: 0.08 μm) Non-surface-treated calcium carbonate (non-surface-treated calcium carbonate, does not contain water (H2O) in molecular form, product name "Whiten SB" manufactured by Shiraishi Calcium Co., Ltd., average particle size: 1.8 μm)

[0135] [Dehydrating agent] Vinyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KBM1003")

[0136] [Adhesion promoter] 3-Glycidoxypropyltrimethoxysilane (tackifier, manufactured by Shin-Etsu Silicones Co., Ltd., product name "KBM403")

[0137] [Aminosilane coupling agent] N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (aminosilane coupling agent, product name "KBM603" manufactured by Shin-Etsu Silicones Co., Ltd.)

[0138] [Silanol condensation catalyst] Dibutyltin diacetylacetonate (manufactured by Nitto Kasei Co., Ltd., product name "U220H") DBU (1,8-diazabicyclo[5.4.0]-7-undecene)

[0139] (Examples 1 to 4, Comparative Examples 1 to 7) The polymer having a hydrolyzable silyl group, the non-surface-treated hydrated metal compound, the surface-treated hydrated metal compound, the thixotropic agent, the low-boiling point liquid compound, the phosphoric acid condensate, the non-phosphoric acid condensate, the filler, the dehydrating agent, the adhesion promoter, the aminosilane coupling agent, and the silanol condensation catalyst shown in Table 1 were mixed in the amounts shown in Table 1 using a planetary mixer under a vacuum atmosphere for 60 minutes until the mixture was uniform, thereby obtaining a curable composition.

[0140] The 100 rpm viscosity and 1 rpm viscosity of the resulting curable composition were measured in the same manner as described above, and the results are shown in Table 1.

[0141] The obtained curable compositions were measured for impact resistance (toughness), spray coatability, flame retardancy, and storage stability in the following manner. The results are shown in Table 1.

[0142] [Impact resistance (toughness)] A 1.5 mm thick test sheet was prepared using the curable composition and aged for 7 days at 23°C and 50% relative humidity to prepare a test coating film. A 500 g weight was dropped onto the test coating film from a height of 50 cm using a DuPont impact tester in accordance with JIS K5600 5-3. The test coating film was evaluated as "○" if no damage was observed, and "×" if damage was observed.

[0143] [Spray coating properties] Using a spray coater sold by PC COX under the product name "Jet Flow Gun 3," the curable composition was spray-coated to a thickness of 0.5 mm onto a flat square surface with sides of 300 mm, taking care not to create pinholes. The coated surface was held vertically downward during spray coating. With the coated surface facing vertically downward, the coating film formed on the coated surface immediately after spray coating was visually observed. The coating film formed from the curable composition was cured at 23°C and a relative humidity of 50% for 7 days to form a coating film. The thickness of the resulting coating film was measured. Evaluation was based on the following criteria.

[0144] 〇 The coating film of the curable composition does not sag when it is uncured, and maintains uniformity. No defects such as pinholes were found in the coating after curing, and the coating thickness was less than 1 mm. Ta. × The coating film sags when the curable composition is uncured and does not maintain uniformity. Pinholes or other defects are found in the coating, or the coating thickness exceeds 1 mm. Part occurred.

[0145] [Flame retardant] A test sheet with a thickness of 1.5 mm was prepared using the curable composition and aged for 7 days at 23°C and a relative humidity of 50% to prepare a test coating film. The test coating film was cut into a flat rectangular shape measuring 15 mm in length and 12.5 mm in width to prepare a test specimen.

[0146] The test was conducted based on the UL94V-0 standard. Specifically, one end of the test specimen was held in a clamp and hung vertically. Next, a 20mm flame from a Bunsen burner was applied to the other end (bottom end) of the test specimen for 10 seconds, and the Bunsen burner was then removed from the test specimen to measure the burning time. V-0 (burning time was less than 10 seconds and the cotton was not ignited by the dripping material.) V-1 (burning time was more than 10 seconds but less than 30 seconds and the cotton was not ignited by the dripping material) V-2 (burning time was more than 10 seconds but less than 30 seconds and cotton was ignited by dripping material) × (The burning time was over 30 seconds.)

[0147] [Storage stability] The viscosity at 100 rpm (initial viscosity) of the curable composition at 23°C was measured using a Brookfield viscometer under conditions of 23°C, 100 rpm, and rotor No. 4 in accordance with JIS K6833.

[0148] The curable composition was sealed in a 330 mL container and allowed to stand for two weeks in an atmosphere at 50°C without contact with moisture. After adjusting the ambient temperature to 23°C, 110 mL of the supernatant liquid of the curable composition in the 330 mL container was removed. The viscosity of this supernatant liquid at 100 rpm at 23°C (viscosity after standing at high temperature) was measured in the same manner as above. The rate of change was calculated based on the following formula. Change rate (%) = 100 x viscosity after high temperature storage / initial viscosity ○ The rate of change was 90% or more and 130% or less. △: The rate of change is 80% or more and less than 90%, or 130% or more and less than 150%. It was. × The rate of change was less than 80% or more than 150%.

[0149] [Table 1] [Industrial Applicability]

[0150] The curable composition of the present invention has a low viscosity that allows it to be applied by spray coating, and has excellent storage stability in that the components are less likely to separate even during storage. Furthermore, upon curing, it can produce a coating film that has excellent toughness and flame retardancy.

[0151] By applying the curable composition of the present invention to a substrate and curing it, a coating film is formed on the substrate, which not only imparts excellent flame retardancy to the substrate or improves the flame retardancy, but also protects the substrate from impact forces.

Claims

1. A curable composition comprising 100 parts by mass of a polymer having a hydrolyzable silyl group, 130 to 300 parts by mass of a surface-untreated hydrated metal compound, a thixotropic agent, and 40 to 150 parts by mass of a low-boiling-point liquid compound, the curable composition having a 100 rpm viscosity at 23°C of 1 to 30 Pa s and a 1 rpm viscosity at 23°C of 100 to 1000 Pa s.

2. 2. The curable composition according to claim 1, wherein the polymer having a hydrolyzable silyl group contains a polymer having a hydrolyzable silyl group having a number average molecular weight of 20,000 to 50,000.

3. 3. The curable composition according to claim 1, wherein the average particle size of the non-surface-treated hydrated metal compound is 0.1 to 10 μm.

4. 3. The curable composition according to claim 1, wherein the composition contains 5 to 50 parts by mass of a phosphoric acid condensate per 100 parts by mass of the polymer having a hydrolyzable silyl group.

5. 3. The curable composition according to claim 1, wherein the curable composition contains 5 to 100 parts by mass of a surface-treated filler per 100 parts by mass of the polymer having a hydrolyzable silyl group.

6. The untreated hydrated metal compounds have a BET specific surface area of ​​3 to 10 m 2 3. The curable composition according to claim 1, wherein the curable composition contains 1 / g of aluminum hydroxide.

7. A coating film produced by curing the curable composition according to claim 1 or 2.

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