Liquid anti-fog coating agent

Abstract

To provide a coating agent capable of forming a coating layer with enhanced anti-fogging properties and an improved appearance.SOLUTION: A liquid coating agent includes (A) elongated colloidal silica, (B) spherical colloidal silica, (C) a silane derivative compound with a polyethylene glycol chain in its molecule, (D) a silane derivative compound with an epoxy group in its molecule (excluding the (C) silane derivative compound), and (E) a solvent including (E1) water, (E2) a first organic solvent with a surface tension of 35 mN / m or more and (E3) a second organic solvent with a surface tension of less than 35 mN / m.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a liquid anti-fog coating agent. [Background technology]

[0002] Anti-fog coating agents are coating solutions that can be applied to the surface of an article to form an anti-fog film, thereby preventing fogging on the surface. They are used in a variety of products, including automobile headlamps, camera lenses, face shields, and eyeglasses.

[0003] In particular, anti-fog coatings used on the inside of automobile headlamp covers (lenses) require long-term durability that is not affected by the external environment. In this case, it is important to suppress water drip marks caused by components leaching from the coating when condensation occurs, as well as to maintain anti-fog properties even after long-term environmental testing.

[0004] Various anti-fog coating agents have been proposed so far. For example, a coating composition that imparts anti-reflection and anti-fog properties to a substrate having a surface onto which the coating composition is applied is known, and that contains a porous inorganic metal oxide and a surfactant containing at least one hydrophobic group and at least one hydrophilic anionic group (Patent Document 1).

[0005] Also, an anti-fogging agent composition comprising a specific copolymer (A), a polyfunctional blocked isocyanate compound (B), and a surfactant (C) has been proposed (Patent Document 2).

[0006] Furthermore, an anti-fog coating composition containing a colloidal silica mixture containing acidic elongated colloidal silica and pH-adjusting elongated colloidal silica is known (Patent Document 3).

[0007] Other known anti-fog coating compositions include one containing long colloidal silica and spherical colloidal silica (Patent Document 4), and one containing long colloidal silica and a silane derivative compound mixture containing at least a silane derivative compound having a polyethylene glycol chain in the molecule and a silane derivative compound having an epoxy group in the molecule (Patent Document 5). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent Publication No. 2010-131651 [Patent Document 2] Patent Publication No. 2016-169287 [Patent Document 3] Patent Publication No. 2019-19253 [Patent Document 4] International Publication WO2021 / 140931 [Patent Document 5] International Publication WO2021 / 141044 Summary of the Invention [Problem to be solved by the invention]

[0009] The applicant of the present application has devised a new highly hydrophilic coating film containing colloidal silica as a main component, as described in Patent Documents 4 and 5 in particular, and has developed an anti-fogging agent that does not leave water drip marks and has excellent anti-fogging durability.

[0010] However, although these conventional techniques can exhibit satisfactory performance in terms of anti-fogging properties, there is still room for further improvement in the appearance of the coating film.

[0011] In anti-fog coatings using inorganic fine particles such as colloidal silica, the primary particle size is maintained by mutual electronic repulsion between the particles. However, depending on the dispersion medium used, particle aggregation is likely to occur, causing a deterioration in the appearance of the transparent film. In particular, when coating by spray coating, there is a problem that particle aggregation is likely to occur at the stage of application to the substrate to be coated. As a result, the coating film may become uneven, known as "citrus peel," or localized aggregation may occur, causing a poor appearance. Therefore, even if the desired anti-fog properties are obtained, such poor appearance may reduce the commercial value of the anti-fog product.

[0012] Therefore, an object of the present invention is to provide a coating agent that can form a coating film that has excellent anti-fogging properties and also has a good appearance. [Means for solving the problem]

[0013] The present inventors have conducted extensive research in light of the problems of the prior art and have found that a composition containing specific components can achieve the above object, thereby completing the present invention.

[0014] That is, the present invention relates to the following liquid anti-fogging coating agent. 1. A liquid coating agent, (A) Long-shaped colloidal silica, (B) spherical colloidal silica, (C) a silane derivative compound having a polyethylene glycol chain in the molecule; (D) Silane derivative compounds having an epoxy group in the molecule (excluding the silane derivative compounds of (C) above), and (E) A solvent containing (E1) water, (E2) a first organic solvent having a surface tension of 35 mN / m or more, and (E3) a second organic solvent having a surface tension of less than 35 mN / m. A liquid anti-fog coating agent comprising: 2. The liquid anti-fog coating agent according to item 1, wherein the surface tension of the first organic solvent is 35 to 72 mN / m, and the surface tension of the second organic solvent is 20 to 30 mN / m. 3. The liquid anti-fog coating agent according to item 1, wherein the boiling point of the first organic solvent is 120°C or higher, and the boiling point of the second organic solvent is 120°C or higher. 4. The liquid anti-fog coating agent according to item 1, wherein the total amount of the solvents is 100% by weight, and the water is 85 to 97% by weight, the first organic solvent is 2 to 10% by weight, and the second organic solvent is 1 to 5% by weight. 5. The liquid anti-fogging coating agent according to item 1, wherein the content of the spherical colloidal silica is 20 to 50 parts by weight out of a total of 100 parts by weight of the elongated colloidal silica and the spherical colloidal silica. 6. As solids content, (A) Long-shaped colloidal silica: 45 to 75% by weight, (B) spherical colloidal silica: 20 to 45% by weight, (C) a silane derivative compound having a polyethylene glycol chain in the molecule: 0.1 to 5% by weight, (D) Silane derivative compound having an epoxy group in the molecule: 0.1 to 5% by weight Item 2. The liquid anti-fog coating agent according to item 1, comprising: 7. The liquid anti-fog coating agent according to item 1, further comprising a surfactant. 8. The liquid anti-fog coating agent according to item 1, which is applied by spraying. 9. A spray product comprising a spray device including a liquid storage section and a spray nozzle for spraying a liquid into the liquid storage section, wherein the liquid storage section is filled with the liquid anti-fogging coating agent according to any one of items 1 to 7. 10. An anti-fogging coating film comprising a coating film of the liquid anti-fogging coating agent according to any one of items 1 to 7 above. 11. An article having the anti-fog coating film according to item 10 laminated on the surface of a substrate. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide a coating agent that can form a coating film that has excellent anti-fogging properties and a good appearance.

[0016] In particular, the liquid anti-fog coating agent of the present invention uses highly hydrophilic inorganic fine particles (spherical silica, elongated silica) as its main component, and an aqueous solvent containing two organic solvents with different surface tensions. Therefore, during film formation (when the coating liquid hardens or solidifies), aggregation that would affect the appearance can be suppressed, while maintaining appropriate gaps between the inorganic fine particles.

[0017] In other words, as a result of being able to suppress such aggregation, a coating film with a good appearance can be formed. Furthermore, by maintaining appropriate gaps between the inorganic fine particles, the water absorption properties due to the gaps can be maintained, and as a result, the high hydrophilicity of the inorganic fine particles can be effectively exhibited, resulting in excellent anti-fogging properties and, ultimately, high anti-fogging durability. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a diagram showing the results of observing the appearance of the coating films of Examples and Comparative Examples (at 20x magnification). DETAILED DESCRIPTION OF THE INVENTION

[0019] 1. Anti-fog coating agent The liquid anti-fogging coating agent of the present invention (the coating agent of the present invention) is (A) Long-shaped colloidal silica (component A), (B) spherical colloidal silica (component B), (C) a silane derivative compound having a polyethylene glycol chain in the molecule (component C), (D) a silane derivative compound having an epoxy group in the molecule (excluding the silane derivative compound (C) above) (component D), and (E) A solvent (component E) containing (E1) water, (E2) a first organic solvent having a surface tension of 35 mN / m or more, and (E3) a second organic solvent having a surface tension of less than 35 mN / m. The present invention is characterized by comprising:

[0020] (1) About each ingredient (1-1) Component A The long colloidal silica of component A is a colloidal solution in which long colloidal silica (SiO2 or its hydrate) in which primary silica particles are covalently bonded to each other to form long strings is dispersed in water. The diameter of the primary silica particles (average primary particle size) is not limited, but is usually about 5 to 300 nm. In the present invention, the long colloidal silica can be spread and adsorbed on the surface of the substrate to form a coating film, and therefore can be suitably used as an active ingredient of the coating agent of the present invention.

[0021] Examples of the long colloidal silica include chain colloidal silica, pearl necklace colloidal silica, etc. The aspect ratio of the long colloidal silica may be, for example, 4 or more, but is not limited thereto.

[0022] Colloidal silica using water as a dispersion medium includes various types: acidic, neutral, and basic. Any of these can be used in the present invention, but particularly examples include acidic long-sized colloidal silica that exhibits a strong acidity of pH 1 to 3 when dispersed in water, neutral long-sized colloidal silica that exhibits a weak acidity, neutrality, or weak basicity of pH 4 to 9, and basic long-sized colloidal silica that exhibits a pH of 10 to 14. These can be used alone or in combination.

[0023] In this case, when a mixture of multiple colloidal silicas is used, they are preferably used in combination so as to maintain a pH range that does not affect the substrate to which the coating agent of the present invention is applied (usually in the weakly acidic to weakly basic range, particularly in the pH range of about 7 to 10). For example, in addition to a combination of acidic long-sized colloidal silica and basic long-sized colloidal silica, or a combination of basic long-sized colloidal silica and acidic long-sized colloidal silica, neutral long-sized colloidal silica can also be used alone.

[0024] Such elongated colloidal silica itself can be a known or commercially available product, such as those under the product names "ST-OUP," "ST-UP," "ST-PS-S," "ST-PS-M," "ST-PS-SO," and "ST-PS-MO" (all manufactured by Nissan Chemical Industries, Ltd.).

[0025] The solid content of component A in the coating agent of the present invention is not limited and can be appropriately set depending on, for example, the desired performance, use, application area, etc., but is usually about 45 to 75 wt %, and preferably 50 to 70 wt %, which can more reliably achieve excellent anti-fogging properties and a good appearance.

[0026] (1-2)B component The spherical colloidal silica, which is component B, is a colloidal solution in which spherical silica (SiO2 or its hydrate) is dispersed in water.

[0027] The spherical colloidal silica has a roughly spherical particle shape in water. Therefore, the aspect ratio of the spherical colloidal silica may be, for example, about 1.5 or less, but is not limited thereto. The diameter (average particle size) of the primary particles of the silica is not limited, but is usually about 5 to 300 nm. In the present invention, two or more types of spherical colloidal silica having different average particle sizes can also be used. This allows for the formation of a denser coating film, which prevents the elution of coating film components and effectively suppresses or prevents the occurrence of "water drip marks" as shown in Test Example 1 below.

[0028] Generally, spherical colloidal silica is acidic, neutral, or basic, but the present invention is directed to basic spherical colloidal silica that contains ammonium ions as described above and exhibits a pH of 10 to 14. These may be used alone or in combination.

[0029] Such spherical colloidal silica can be a known or commercially available product. Examples of commercially available basic spherical colloidal silica include those with the product names "ST-N," "ST-NS," and "ST-N-40" (all manufactured by Nissan Chemical Industries, Ltd.). Examples of acidic spherical colloidal silica include those with the product names "ST-O," "ST-OS," and "ST-O-40" (all manufactured by Nissan Chemical Industries, Ltd.).

[0030] The solid content of component B in the coating agent of the present invention is not limited and can be appropriately set depending on, for example, the desired performance, use, application area, etc., but is usually about 20 to 45 wt %, and preferably 25 to 40 wt %. By setting it within the above range, excellent anti-fogging properties and a good appearance can be more reliably obtained.

[0031] The ratio of component A to component B is not limited, but is preferably 20 to 50 parts by weight, and more preferably 25 to 40 parts by weight, of 100 parts by weight of the total of both components, thereby achieving better film-forming properties, anti-fogging durability (water drip marks), and better appearance.

[0032] (1-3)C component A silane derivative compound having a polyethylene glycol chain in the molecule is used as component C. Specifically, at least one of the compounds represented by the following general formulas (1-1) to (1-3) can be used.

[0033] As the compound represented by general formula (1-1), [ka] (In the formula, R 1 , R 2 and R 3 are the same or different and are alkyl groups having 1 to 3 carbon atoms, and R 4is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, n is an integer of 1 to 5, and m is an integer of 1 to 20, preferably 4 to 20, and more preferably 4 to 15.

[0034] The silane derivative compound represented by the general formula (1-1) has an alkoxy group (i.e., -OR) capable of reacting with the long-shaped silica and the spherical silica. 1 , -OR 2 and-OR 3 The silane derivative compound represented by general formula (1-1) has a substituent group capable of reacting with long-sized silica and a hydrophilic group (-OCH2CH2-), and the silane derivative compound can bond to the long-sized silica and the spherical silica, and can impart hydrophilicity to the coating film formed by the coating agent of the present invention.

[0035] Specific examples of the silane derivative compound represented by general formula (1-1) include polyethylene glycol-modified alkoxysilanes such as methoxy PEG-10 propyl trimethoxysilane and ethoxy PEG-10 propyl trimethoxysilane. Other examples that can be used include 2-[hydroxy(polyethyleneoxy)ethyl]trimethoxysilane, 3-[hydroxy(polyethyleneoxy)propyl]trimethoxysilane, 4-[hydroxy(polyethyleneoxy)butyl]trimethoxysilane, 2-[alkoxy(polyethyleneoxy)ethyl]trimethoxysilane, 3-[alkoxy(polyethyleneoxy)propyl]trimethoxysilane, and 4-[alkoxy(polyethyleneoxy)butyl]trimethoxysilane.

[0036] The silane derivative compound represented by general formula (1-1) itself can be a commercially available product, such as those under the product names "Dynasylan 4148" and "Dynasylan 4150" (both from Evonik Japan Co., Ltd.) and "Methoxy PEG-10 Propyl Trimethoxysilane" (PG series) (Azmax Co., Ltd.).

[0037] Further, as the compound represented by the general formula (1-2), [ka] (In the formula, R 11 , R 12 , R 13 and R 14 are the same or different and are alkyl groups having 1 to 3 carbon atoms, A is selected from the group consisting of -O-, -NHCOO-, -OCO-, -COO-, -OCH2CH(OH)CHO-, -OCH2CH2CH(OH)O-, -S-, -SCO- and -COS-, n1 is an integer of 1 to 5, and m1 is an integer of 1 to 20, preferably 4 to 20, and more preferably 4 to 15.) can be used. Of the silane derivative compounds represented by general formula (1-2), the most preferred group for A in the formula is -O-.

[0038] The silane derivative compound represented by the general formula (1-2) has an alkoxy group (i.e., -OR) that can react with the long-shaped silica. 11 , -OR 12 and OR 13 group) and a hydrophilic group (-CH2CH2O-) containing a polyethylene glycol chain that has a high affinity for water.

[0039] The silane derivative compound represented by the general formula (1-2) has a substituent capable of reacting with the long-shaped silica and a hydrophilic group, and therefore the silane derivative compound can bond to the long-shaped silica and can impart hydrophilicity to the coating film formed by the coating agent of the present invention.

[0040] Specific examples of the silane derivative compound represented by general formula (1-2) include 3-[acetoxy(polyethyleneoxy)propyl]triethoxysilane, 2-[acetoxy(polyethyleneoxy)ethyl]trimethoxysilane, 3-[acetoxy(polyethyleneoxy)propyl]trimethoxysilane, and 4-[acetoxy(polyethyleneoxy)butyl]trimethoxysilane.

[0041] The silane derivative compound represented by general formula (1-2) itself can be a known or commercially available product, such as 3-[acetoxy(polyethyleneoxy)propyl]triethoxysilane (Gelest Inc.), which is a silane derivative compound having a polyethylene glycol chain and an acyl group in the molecule.

[0042] As the compound represented by the general formula (1-3), [ka] (In the formula, R 21 , R 22 and R 23 are the same or different and each is an alkyl group having 1 to 3 carbon atoms, and R 24 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, B is selected from the group consisting of -NHCOO-, -OCO-, -COO-, -OCH2CH(OH)CHO-, -OCH2CH2CH(OH)O-, -S-, -SCO- and -COS-, n2 is an integer of 1 to 5, and m2 is an integer of 1 to 20, preferably 4 to 20, and more preferably 4 to 15.) can be used. Of the silane derivative compounds represented by general formula (1-3), the most preferred group for B in the formula is -NHCOO- (a urethane group).

[0043] The silane derivative compound represented by the general formula (1-3) has an alkoxy group (i.e., -OR) that can react with the long-shaped silica. 21 , -OR 22 and-OR 23 group) and a hydrophilic group (-CH2CH2O-) containing a polyethylene glycol chain that has a high affinity for water.

[0044] The silane derivative compound represented by the general formula (1-3) has a substituent capable of reacting with the long-shaped silica and a hydrophilic group, and therefore the silane derivative compound can bond to the long-shaped silica and can impart hydrophilicity to the coating film formed by the coating agent of the present invention.

[0045] Specific examples of the silane derivative compound represented by general formula (1-3) include 2-hydroxy(polyethyleneoxy)ethyl [3-(trimethoxysilyl)propyl]carbamate, 2-hydroxy(polyethyleneoxy)ethyl [3-(triethoxysilyl)propyl]carbamate, 2-alkoxy(polyethyleneoxy)ethyl [3-(trimethoxysilyl)propyl]carbamate, 2-alkoxy(polyethyleneoxy)ethyl [3-(triethoxysilyl)propyl]carbamate, and 2-alkoxy(polyethyleneoxy)ethyl [4-(trimethoxysilyl)butanoic acid] ester.

[0046] Among the silane derivative compounds represented by general formula (1-3), those having a polyethylene glycol chain and a urethane group in the molecule are most preferred. The silane derivative compounds having a polyethylene glycol chain and a urethane group in the molecule can be synthesized by reacting an alkoxysilane compound having an isocyanato group, such as isocyanatopropyltrimethoxysilane or isocyanatopropyltriethoxysilane, with polyethylene glycol.

[0047] In this specification, among the silane derivative compounds represented by general formula (1-3), silane derivative compounds having a polyethylene glycol chain and a urethane group in the molecule, which can be particularly suitably used in the embodiments, may be referred to as "urethane silane." Furthermore, the silane derivative compounds represented by general formulas (1-1), (1-2), and (1-3) may be collectively referred to as "silane derivative compounds having a polyethylene glycol chain in the molecule."

[0048] The solid content of component C in the coating agent of the present invention is not limited and can be appropriately set depending on, for example, the desired performance, use, application area, etc., but is usually about 0.1 to 5 wt %, and preferably 1 to 4 wt %. By setting it within the above range, it is possible to more reliably obtain excellent anti-fogging properties and a good appearance.

[0049] (1-4)D component A silane derivative compound having an epoxy group in the molecule (excluding the silane derivative compound (C)) is used as component D. As component D, a silane derivative compound represented by general formula (2) can be used. [ka] (In the formula, R 5 , R 6 and R 7 are the same or different and are alkyl groups having 1 to 3 carbon atoms, p is an integer of 1 to 5, and X is an organic group containing an epoxy group.

[0050] This is because the alkoxy groups (i.e., -OR) that can react with the elongated silica. 5 , -OR 6 and OR 7 and X (X is an organic group containing an epoxy group). Here, examples of the organic group containing an epoxy group include, but are not limited to, a glycidyl group.

[0051] The silane derivative compound represented by the general formula (2) has a substituent that can react with the long-sized silica, and therefore the silane derivative compound can crosslink between the long-sized silica particles.

[0052] Specific examples of the silane derivative compound represented by general formula (2) include epoxy group-containing silane derivative compounds such as 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, and 3-glycidoxypropylmethyldiethoxysilane.

[0053] As the silane derivative compound having an epoxy group in the molecule, for example, commercially available products such as "Dynasylan GLYEO" (Evonik Japan Co., Ltd.), "KBM402", "KBM403", "KBE402", and "KBE403" (all manufactured by Shin-Etsu Chemical Co., Ltd.) can be used. Such silane derivative compounds react with and bond to long-sized silica particles, cross-linking the long-sized silica particles, increasing the strength of the coating film and imparting hydrophilicity to the coating film.

[0054] The solid content of component D in the coating agent of the present invention is not limited and can be appropriately set depending on, for example, the desired performance, use, application area, etc., but is usually about 0.1 to 5 wt %, and preferably 1 to 4 wt %. By setting it within the above range, excellent anti-fogging properties, good appearance, etc. can be more reliably obtained.

[0055] (1-6)E component Component E is a solvent (aqueous solvent) containing (E1) water, (E2) a first organic solvent having a surface tension of 35 mN / m or more, and (E3) a second organic solvent having a surface tension of less than 35 mN / m. The use of such a specific aqueous solvent makes it possible to form a coating film with excellent appearance (particularly a coating film with excellent coating film leveling and effectively suppressing the formation of orange peel, aggregates, etc.), especially when the coating agent of the present invention is applied by spraying.

[0056] The mechanism by which a coating film with both high anti-fogging properties and excellent appearance is formed in the present invention is unclear. However, when the first organic solvent alone is used, the inorganic fine particles dry (cure) while maintaining their primary particle size, forming a dense coating film with no gaps, which results in the desired water absorption and in unsatisfactory anti-fogging properties. On the other hand, when the second organic solvent alone is used, the inorganic fine particles dry (cure) while forming secondary particle sizes, forming a coating film with many aggregated particles, resulting in poor appearance. Based on these findings, it is presumed that the combined use of the first and second organic solvents maintains appropriate gaps while suppressing aggregation that would otherwise cause poor appearance, resulting in the formation of a coating film with both excellent anti-fogging properties and good appearance. Thus, in the present invention, the combined use of the first and second organic solvents can achieve effects that cannot be achieved by either the first or second organic solvent alone, thereby achieving a synergistic effect of the two organic solvents.

[0057] Various types of water can be used, such as pure water, ultrapure water, and tap water. The amount of water contained in 100% by weight of component E is not limited, but is usually about 85 to 97% by weight, and preferably 90 to 96% by weight. If the amount of water is too little, the dispersion stability of the inorganic fine particles may decrease. If the amount of water is too much, the surface tension of the coating liquid may decrease, which may result in a decrease in the leveling properties of the coating film.

[0058] The first organic solvent generally has a surface tension of 35 mN / m or more, preferably 35 to 72 mN / m, and more preferably 50 to 72 mN / m. A first organic solvent having such a surface tension has a function of suppressing particle aggregation in the coating agent of the present invention.

[0059] Specific examples of the first organic solvent include at least one of dipropylene glycol, propylene glycol, 1,2 butanediol, 1,3 butanediol, and 1,4 butanediol.

[0060] The content of the first organic solvent in 100% by weight of component E is not limited, but is usually about 2 to 10% by weight, and preferably 3 to 9% by weight. If the amount of the first organic solvent is too small, particle aggregation may occur easily, which may deteriorate the appearance of the coating film. On the other hand, if the amount of the first organic solvent is too large, the coating film may become too dense and the desired anti-fogging effect may not be obtained.

[0061] The second organic solvent usually has a surface tension of less than 35 mN / m, preferably 20 to 30 mN / m. A second organic solvent having such a surface tension has the function of increasing the porosity of the coating film in the coating agent of the present invention.

[0062] Specific examples of the second organic solvent include at least one of diethylene glycol monobutyl ether, 1-methoxy-2-propanol, isopropyl alcohol, diethylene glycol monoethyl ether, and diethylene glycol monomethyl ether.

[0063] The content of the second organic solvent in 100% by weight of component E is not limited, but is usually about 1 to 5% by weight, and preferably 1 to 3% by weight. If the amount of the second organic solvent is too small, the porosity of the coating film may become too low, and the anti-fogging effect due to water absorption may not be obtained. Furthermore, if the amount of the second organic solvent is too large, particle aggregation may occur more easily, which may deteriorate the appearance of the coating film.

[0064] In the coating agent of the present invention, the ratio (weight ratio) of the first organic solvent to the second organic solvent can be set, for example, in the range of about first organic solvent:second organic solvent = (1.5 to 3.5):1, but is not limited to this.

[0065] In the present invention, both the first organic solvent and the second organic solvent are preferably high-boiling point solvents. More specifically, both preferably have boiling points of 120°C or higher (particularly 150 to 250°C). By using such high-boiling point solvents, an appropriate evaporation time is ensured, and a coating film with a good appearance can be formed.

[0066] The surface tensions of the first and second organic solvents can be measured at a measurement temperature of 25°C by the Wilhelmy plate method.

[0067] In the present invention, the solvent, which is component E, is preferably a solution (mixed solution) in which the first organic solvent and the second organic solvent are dissolved in water, but it is not necessary for all of them to be completely dissolved as long as the effects of the present invention are not hindered.

[0068] The content of component E in the coating agent of the present invention may be appropriately determined depending on, for example, the coatability and film-forming properties of the coating agent of the present invention. For example, it can be set so that the solid content concentration of the coating agent of the present invention is about 5 to 90% by weight, and preferably can be set so that it is within the range of 5 to 50%, but is not limited thereto.

[0069] (1-7) Other ingredients The coating agent of the present invention can be appropriately blended with additives typically contained in paint compositions (such as surfactants, dyes, pigments, plasticizers, dispersants, preservatives, matting agents, antistatic agents, and flame retardants) within a range that does not impair the effects of the present invention. The surfactant may be an anionic surfactant, cationic surfactant, nonionic surfactant, or amphoteric surfactant. The addition of a surfactant allows the coating agent of the present invention to be applied more smoothly to the substrate. When a surfactant is used, the amount can be set to, for example, about 0.01 to 0.3 wt % in the coating agent of the present invention, but is not limited to this.

[0070] (2) Properties of the Coating Agent of the Present Invention The coating agent of the present invention can usually be used in liquid form. In this case, as described above, component E is used as a solvent. The viscosity and other properties of the coating agent of the present invention can be appropriately set depending on the application, type of substrate, etc.

[0071] In particular, when the coating agent of the present invention is applied by a spray method, the viscosity (25° C.) is preferably about 1 to 100 mPa·s, but this can be appropriately set depending on the specifications of the spray device, etc.

[0072] 2. Production of the coating agent of the present invention The coating agent of the present invention can be produced by uniformly mixing the above-mentioned components. The order of mixing is not particularly limited, and the components may be mixed simultaneously or sequentially.

[0073] The mixing can also be carried out using known or commercially available devices such as a mixer or kneader.

[0074] 3. Use of the coating agent of the present invention The coating agent of the present invention can be applied to the surface of a substrate in the same manner as known or commercially available anti-fog coating agents, to form a coating film (anti-fog coating film) made from the coating agent of the present invention as a cured film on the surface of the substrate. The present invention also includes such anti-fog coating films made from the coating agent of the present invention.

[0075] The material of the substrate is not particularly limited and may be, for example, plastic, glass, metal, ceramic, rubber, etc. The substrate may also be a material constituting a raw material, a primary product, or a final product. Examples of the final product include lighting devices, headlights (covers, lenses, etc.), windows, lenses, lens covers, monitors, monitor covers, eyeglasses / sunglasses, goggles, face shields, face guards, helmets, etc. Thus, articles in which an anti-fog coating film made from the coating agent of the present invention is laminated on the surface of a substrate constituting the article are also encompassed by the present invention.

[0076] The article of the present invention, which includes an anti-fog coating film, possesses excellent anti-fog properties due to the coating film. Moreover, even when the article is exposed to unexpectedly high temperatures, the formation of water drip marks and other defects can be effectively suppressed, maintaining a good appearance. Furthermore, the coating film produced by the coating agent of the present invention adheres firmly to substrates such as plastics and has high adhesion, making it highly durable at high temperatures and able to exhibit anti-fog properties for a long period of time. Furthermore, the coating film can also suppress the formation of orange peel and aggregates, which are prone to occur with conventional coating agents, thereby achieving a good appearance.

[0077] The method for applying the coating agent of the present invention to a substrate is not limited, and various coating methods can be used, such as a doctor blade method, a bar coating method, a dipping method, a spray method (air spray method), a roller brush method, and a roller coater method.

[0078] The coating agent of the present invention is particularly suitable for application by spraying. While conventional coating agents tend to have poor coating film appearance, the coating agent of the present invention can more reliably form a coating film that suppresses orange peel and the formation of aggregates, even when applied by spraying. Therefore, the present invention also encompasses a spray product in which a liquid container and a spray nozzle that sprays a liquid into the liquid container are filled with the coating agent of the present invention.

[0079] The spray device itself is not limited, and any known or commercially available device can be used. The spray device may be either manual or electric. Therefore, for example, the coating agent of the present invention can be filled into the liquid reservoir of a commercially available spray device and used (sprayed) under normal conditions.

[0080] The coating thickness is not particularly limited, and may be adjusted so that the thickness of the anti-fogging coating film that is finally formed falls within the range of about 0.1 to 10 μm, but is not limited thereto.

[0081] After coating, the wet coating film can be dried to form an anti-fogging coating film. Drying can be natural drying, but is preferably heated drying. The temperature during heated drying should be high enough to allow the silica and the silane derivative to react and to evaporate the solvent. The heating temperature can be, for example, about 80 to 150°C, and particularly 100 to 140°C. This allows the reaction to proceed smoothly and the solvent to evaporate.

[0082] The heating means is not particularly limited, and can be, for example, heating with a heating device such as a burner or oven, or a heating method using hot air from a dryer or the like. When the coating film of the coating agent of the present invention dries in this way, the elongated colloidal silica (and optionally spherical colloidal silica) spread on the substrate surface becomes elongated silica (optionally spherical silica) to form a predetermined cured film. Meanwhile, the silane derivative compound bonds with these silica particles and crosslinks between the silica particles to form a strong high-order structure.

[0083] Thus, by applying the coating agent of the present invention to an article, an anti-fogging coating film can be formed, resulting in the production of an article coated with such a coating film. At the same time, the specific solvent, which is component E of the present invention, aligns the inorganic fine particles, i.e., silica particles, while maintaining appropriate gaps, upon evaporation, so that a coating film with a relatively smooth and uniform surface can be formed, thereby giving the coating film a good appearance.

[0084] The article of the present invention has excellent anti-fogging properties due to its coating film. Moreover, as described above, by forming a coating film using two types of colloidal silica in combination in the presence of a specific solvent, it is possible to effectively suppress phenomena that cause noticeable changes in appearance, such as the formation of aggregates, orange peel, and water drip marks, even when the article is exposed to unexpectedly high temperature conditions. Furthermore, the coating film formed by the coating agent of the present invention firmly adheres to substrates such as plastics and has high adhesion, so it is highly durable at high temperatures and can maintain anti-fogging properties for a long period of time. [Example]

[0085] The features of the present invention will be described in more detail below with reference to examples and comparative examples, but the scope of the present invention is not limited to these examples.

[0086] Examples 1 to 4 A liquid coating agent was prepared by uniformly mixing the components shown in Table 1. The content of each component is expressed in "% by weight."

[0087] Comparative Examples 1 to 4 A liquid coating agent was prepared in the same manner as in Example 1, except that the composition was changed as shown in Table 1.

[0088] [Table 1]

[0089] The meanings of the abbreviations in Table 1 are as follows: "ST-OUP": Snowtex OUP, Nissan Chemical Industries, Ltd., acidic elongated colloidal silica (solid content 15% by weight, aqueous dispersion) "ST-UP": Snowtex UP, Nissan Chemical Industries, Ltd., Na + Contains basic long colloidal silica (solid content 20% by weight, aqueous dispersion) "ST-N": Snowtex N, Nissan Chemical Industries, Ltd., NH4 with a particle size of 12 nm + Contains spherical basic colloidal silica (solid content 20% by weight, aqueous dispersion) "ST-NXS": Snowtex NXS, Nissan Chemical Industries, Ltd., NH4 with a particle size of 5 nm + Contains basic spherical colloidal silica (solid content 15% by weight, aqueous dispersion) "FT-150": Futergent 150, Neos Co., Ltd., anionic surfactant (solid content 100% by weight) "D-4148": Dynasylan 4148, Evonik Japan Co., Ltd., a silane derivative compound with a polyethylene glycol chain in the molecule (solid content 100% by weight) "KBM-403": Shin-Etsu Chemical Co., Ltd., silane derivative compound with an epoxy group in the molecule (solid content 100% by weight) DPG: Dipropylene glycol (boiling point 230°C, surface tension 71.4mN / m) 1,3-BD: 1,3-butanediol (boiling point 208°C, surface tension 37.8mN / m) BDG: Diethylene glycol monobutyl ether (boiling point 231°C, surface tension 29.1mN / m) "PGM": 1-methoxy-2-propanol (boiling point 120°C, surface tension 27.7mN / m)

[0090] Test Example 1 A coating film was formed on a substrate using the coating agent prepared in each of the Examples and Comparative Examples to prepare a sample. The coating agent was applied to a 1 mm thick polycarbonate substrate. The application was performed by spray coating, and the amount of coating was adjusted so that the thickness of the coating film (cured film) after the coating agent cured would be 1 μm. The substrate coated with the coating agent was placed in an oven at 110°C and heated for 15 minutes to form a cured film, thereby obtaining a sample. The obtained sample was used to evaluate various performances using the methods described below.

[0091] (1) Zeta potential The zeta potential of the coating agent was measured using Otsuka Electronics' "ELSZ-1000." Zeta potential is the potential difference between the slip surface in the electric double layer and a portion sufficiently distant from the interface, and is an important parameter in controlling the state of particle aggregation in the coating film, as it can be used to evaluate the electrostatic repulsion characteristics (≒ cohesion) between particles.

[0092] (2) Porosity The surface of the cured film was observed using a field emission scanning electron microscope (FE-SEM), and the obtained image was used to calculate the percentage of voids on the coating surface. More specifically, the grayscale image was binarized, the brightness range of the voids was set, and the area ratio of the voids to the entire image was then read and calculated using software.

[0093] (3) Coating appearance The appearance of the cured film was observed visually and under a microscope to check the leveling state and film smoothness. As a result, cases where no particular abnormalities were observed were marked with "○", and cases where leveling or a granular appearance due to particle agglomerations was observed were marked with "×". For reference, the observation results of Example 1 and Comparative Example 3 (20x magnification) are shown in Figure 1. Figure 1A shows the observation results of Example 1. Figure 1B shows the observation results of Comparative Example 2. In Figure 1A, the surface does not have a granular appearance, and the surface has a good appearance. The granular objects in Figure 1A are thought to be secondary agglomerates of particles (colloidal silica components, etc.), but these are minute agglomerates that do not impair the appearance of the coating film, do not affect the effects of the present invention, and are not a problem in practical use. In Figure 1B, the entire surface has a granular (island-like) appearance, and agglomeration is noticeable.

[0094] (4) Haze Measurement was performed using a haze meter in accordance with Japanese Industrial Standard JIS K 7136. A haze value of less than 0.7 was marked as "Good", and a haze value of 0.7 or more was marked as "Poor".

[0095] (5) Anti-fogging The sample was placed with the coating facing downwards at a height of 1 cm above the water surface in a 40°C hot water bath, and steam from the hot water bath was applied to the coating for 10 seconds. During this time, the coating was visually inspected for the formation of cloudiness. If no cloudiness was observed on the coating, it was marked "Good", and if cloudiness was observed, it was marked "Poor".

[0096] (6) Water dripping resistance The sample subjected to the anti-fogging evaluation in (2) above was left standing vertically for 30 minutes to dry, and the presence or absence of water drip marks on the sample surface was visually confirmed. If no water drip marks were observed, the sample was marked with "○", and if water drip marks were observed, the sample was marked with "×".

[0097] (7) Anti-fog properties after durability test The sample was left standing in an environment of a temperature of 50° C. and a humidity of 95% for 240 hours, and then the anti-fogging property was evaluated as described in (5) above.

[0098] As is clear from the results in Table 1, Examples 1 to 4 contained the solvent of the present invention, had a zeta potential within the range of −27 to −33 mV, and had good appearance and anti-fogging durability.

[0099] In Comparative Example 1, a high boiling point solvent was not blended, and the coating could not be applied uniformly to the polycarbonate substrate.

[0100] In Comparative Example 2, since a high-boiling point solvent with a surface tension of less than 35 mN / m was not blended, the porosity was low and the anti-fogging durability was insufficient.

[0101] In Comparative Example 3, a sufficient amount of high-boiling solvent with a surface tension of 35 mN / m or more was blended, but the amount of high-boiling solvent with a surface tension of less than 35 mN / m was too high, resulting in a granular surface (poor appearance).

[0102] In Comparative Example 4, the surface was granular (poor appearance) because a high boiling point solvent with a surface tension of 35 mN / m or more was not blended. [Industrial Applicability]

[0103] The coating agent of the present invention can be applied to the surface of a substrate to form an anti-fogging coating film, which makes it possible to provide various anti-fogging articles (e.g., lighting devices, headlights, windows, lenses, lens covers, monitors, monitor covers, eyeglasses / sunglasses, goggles, face shields, face guards, helmets, etc.).

Claims

1. A liquid coating agent, (A) long-shaped colloidal silica, (B) spherical colloidal silica, (C) a silane derivative compound having a polyethylene glycol chain in the molecule; (D) a silane derivative compound having an epoxy group in the molecule (excluding the silane derivative compound (C) above), and (E) A solvent containing (E1) water, (E2) a first organic solvent having a surface tension of 35 mN / m or more, and (E3) a second organic solvent having a surface tension of less than 35 mN / m, In a total of 100% by weight of the solvents, water accounts for 85 to 97% by weight, the first organic solvent accounts for 2 to 10% by weight, and the second organic solvent accounts for 1 to 5% by weight, and the ratio (weight ratio) of the first organic solvent to the second organic solvent is first organic solvent:second organic solvent=(1.5 to 3.5):1; A liquid anti-fogging coating agent characterized by:

2. 2. The liquid anti-fog coating agent according to claim 1, wherein the first organic solvent has a surface tension of 35 to 72 mN / m, and the second organic solvent has a surface tension of 20 to 30 mN / m.

3. 2. The liquid anti-fog coating agent according to claim 1, wherein the boiling point of the first organic solvent is 120°C or higher, and the boiling point of the second organic solvent is 120°C or higher.

4. A liquid anti-fog coating agent as described in claim 1, wherein the second organic solvent is 1 to 3 wt% out of a total of 100 wt% of the solvents.

5. The first organic solvent is at least one of dipropylene glycol, propylene glycol, 1,2 butanediol, 1,3 butanediol, and 1,4 butanediol; 2. The liquid anti-fog coating agent according to claim 1, wherein the second organic solvent is at least one of diethylene glycol monobutyl ether, 1-methoxy-2-propanol, isopropyl alcohol, diethylene glycol monoethyl ether, and diethylene glycol monomethyl ether.

6. 2. The liquid anti-fogging coating agent according to claim 1, wherein the content of the spherical colloidal silica is 20 to 50 parts by weight out of a total of 100 parts by weight of the elongated colloidal silica and the spherical colloidal silica.

7. As solid content, (A) Long-sized colloidal silica: 45 to 75% by weight, (B) spherical colloidal silica: 20 to 45% by weight, (C) a silane derivative compound having a polyethylene glycol chain in the molecule: 0.1 to 5% by weight, (D) Silane derivative compound having an epoxy group in the molecule: 0.1 to 5% by weight The liquid anti-fog coating agent of claim 1 , comprising:

8. The liquid anti-fog coating agent of claim 1 further comprising a surfactant.

9. 10. The liquid anti-fog coating agent according to claim 1, which is applied by spraying.

10. A spray product comprising a spray device including a liquid storage section and a spray nozzle for spraying a liquid into the liquid storage section, wherein the liquid storage section is filled with the liquid anti-fogging coating agent according to any one of claims 1 to 8.

11. An anti-fogging coating film comprising a coating film of the liquid anti-fogging coating agent according to any one of claims 1 to 8.

12. An article having the anti-fogging coating film described in claim 11 laminated on the surface of a substrate.

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