Surface anti-reflective coating film, optical components and surface anti-reflective paint

Abstract

The present invention can provide a surface antireflection film in which particles are unlikely to fall from a coating film and which has a low total reflectance.　A surface antireflection coating film according to the present invention comprises a binder resin, carbon black, and silica, said surface antireflection coating film being characterized in that: said surface antireflection coating film has an arithmetic average roughness (Ra) of 0.3-3.0 μm and a developed length ratio (Rlr) of not less than 1.6; the carbon black has a specific surface area of 175-400 m2 / g; the content of the carbon black is 2.5-28.0 parts by mass with respect to 100 parts by mass of the binder resin; and the content of the silica is 16.0-28.0 parts by mass with respect to 100 parts by mass of the binder resin.<sp / >

Description

[Technical Field]

[0001] The present invention relates to a surface antireflection coating film, an optical element using the surface antireflection coating film, and a surface antireflection paint for forming the surface antireflection coating film. [Background technology]

[0002] In optical devices such as cameras and video cameras, stray light caused by diffuse reflection or scattering in the optical path of the lens barrel, etc., can cause ghosts and flares in the formed image, which can be one of the causes of image quality degradation. To prevent this degradation of optical performance due to stray light, black surface anti-reflective paint is applied to the optical path of the lens barrel, aperture, etc., forming a surface anti-reflective coating film, or applying a surface anti-reflective film.

[0003] On the other hand, black surface anti-reflective coatings and surface anti-reflective films are not only used in optical devices such as cameras, but are also being used as optical components to improve visibility by preventing peripheral reflection in luminous display devices such as automobile meters and head-up displays. In addition, black surface anti-reflective coatings and films are also attracting attention as paints that improve design.

[0004] Patent Document 1 proposes a coating material for forming a surface anti-reflection film, which is composed of a binder resin, carbon black, hydrophobized dry silica, and polyamide resin particles. Furthermore, Patent Document 2 proposes a coating material that is composed of a resin component and two types of inorganic particles, one with a small particle size and the other with a large particle size. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2019 / 124202 [Patent Document 2] Japanese Patent Publication No. 2023-16200 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the total reflectance of light (hereinafter also referred to as "total light reflectance") of a coating film formed using the anti-reflective coating described in Patent Document 1 is excellent. However, because large resin particles with an average particle size of 10 μm to 20 μm are used, there is a problem of particle shedding due to reduced adhesion between the binder and the resin particles. Furthermore, Patent Document 2 discloses a coating film formed by spray coating using a coating material that does not contain large particles, and the spray coating is carried out using a coating material with a high amount of particles added per 100 parts by mass of resin. In spray coating, the sprayed droplets are dried and hardened to form a film. When a large amount of particles is added, there is a concern that the coating surface may shedding depending on the degree of adhesion of the droplets that make up the film, and there is also room for improvement in terms of total reflectance. Therefore, an object of the present invention is to provide a front surface anti-reflective coating film which is free from the risk of particles falling off and has a low total reflectance. [Means for solving the problem]

[0007] The present invention provides a surface anti-reflective coating film containing a binder resin, carbon black, and silica, wherein the surface anti-reflective coating film has an arithmetic mean roughness (Ra) of 0.3 μm or more and 2.0 μm or less, a developed length ratio (Rlr) of 1.6 or more, and a specific surface area of ​​the carbon black of 175 m 2 / g or more 400m 2 / g or less, the carbon black content is 2.5 parts by mass or more and 28.0 parts by mass or less relative to 100 parts by mass of the binder resin, and the silica content is 16.0 parts by mass or more and 26.0 parts by mass or less relative to 100 parts by mass of the binder resin. The present invention also provides an optical member having the above-described surface antireflection film. The present invention also provides a surface anti-reflection coating material containing a binder resin, carbon black, and silica, wherein the specific surface area of ​​the carbon black is 175 m 2 / g or more 400m 2 / g or less, the content of the carbon black is 2.5 parts by mass or more and 28.0 parts by mass or less with respect to 100 parts by mass of the binder resin, and the specific surface area of ​​the silica is 130 m 2 / g or more 400m 2 / g or less, and the content of the silica is 16.0 parts by mass or more and 28.0 parts by mass or less relative to 100 parts by mass of the binder resin. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a front surface anti-reflective coating film that has a low total reflectance and is free from the risk of the contained particles falling off. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a scanning electron microscope photograph showing the surface state in Example 1. [Figure 2] 1 is a scanning electron microscope photograph showing the surface state in Comparative Example 1. [Figure 3] FIG. 2 is a diagram illustrating a method for measuring total light reflectance. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the surface anti-reflective coating film may be simply referred to as a "coating film" and the surface anti-reflective paint may be simply referred to as a "paint." The front surface anti-reflective coating film according to the present invention contains a binder resin, carbon black, and silica.

[0011] The coating film of the present invention is preferably free from large irregularities that could lead to peeling of the coating film as a whole, and is smooth macroscopically, but has fine irregularities formed microscopically, as shown in Figure 1. The surface shown in Figure 2 is smooth macroscopically, but does not have fine irregularities formed microscopically, which is undesirable as it results in a high total reflection value. In this embodiment, the surface roughness of the front-surface antireflection coating film must be such that the arithmetic mean roughness (Ra) is 0.3 μm or more and 2.0 μm or less, and the developed length ratio (Rlr) is 1.6 or more. By ensuring that Ra is 0.3 μm or more and Rlr is 1.6 or more, a coating film with densely packed fine irregularities can be obtained, and these irregularities can absorb light and reduce reflection. Furthermore, by ensuring that Ra is 2.0 μm or less, particle shedding due to the irregularities can be prevented. Surface roughness was measured using a non-contact laser measuring device. Specifically, a color 3D laser microscope VK-8710 (manufactured by Keyence Corporation) with a 100x standard objective lens (CF IC EPI Plan 100X) was used. Surface data was measured at a measurement pitch of 0.2 μm. Roughness was calculated using the accompanying software VK-Analyzer (manufactured by Keyence Corporation). A straight line with a measurement length of 140 μm was extracted from the measured surface data, and Ra and Rlr were calculated under the conditions of no cutoff value λs and no cutoff value λc. The average values ​​of n = 3 were calculated and used as Ra and Rlr. The arithmetic mean roughness (Ra) represents the average of the absolute values ​​of the irregularities in the measurement length, and is calculated by the following formula.

number

number

[0012] The carbon black content is 2.5 to 28.0 parts by mass per 100 parts by mass of binder resin. Preferably, it is 11.0 to 28.0 parts by mass, and more preferably, it is 13.0 to 25.0 parts by mass. If it is 2.5 parts by mass or more, it can properly form unevenness together with the silica described below, keeping the total reflection value low and sufficiently shielding light. The shielding effect reduces the amount of light that passes through the coating film and reaches the substrate. Light that passes through the coating film may be reflected by the substrate, affecting the total reflection and color of the coating film, so it is preferable to use less. Furthermore, if it is 28.0 parts by mass or less, the viscosity of the paint does not increase too much, allowing for coatability to be maintained. If it is 25.0 parts by mass or less, better coatability is achieved and the total reflection value can be further reduced. In the present invention, 100 parts by mass of binder resin refers to the total amount including the binder resin and the curing agent when the coating film or paint contains a curing agent, and refers to the amount of solids excluding the solvent when the coating film or paint contains a solvent.

[0013] The carbon black used in the present invention has a specific surface area determined by nitrogen adsorption of 175 m 2 / g or more 400m 2 / g or less. Generally, when the specific surface area due to nitrogen adsorption is large, the primary particle size of carbon black becomes small, and there are many fine particles, which is thought to increase the probability that the particles will be exposed to light. When the specific surface area due to nitrogen adsorption is 175m 2 / g or more, the reflection can be kept low. 2 If the specific surface area exceeds 1 / g, the viscosity of the paint will increase too much, making it difficult to maintain coatability. Here, the specific surface area of ​​carbon black can be determined by a measurement method in accordance with JIS K6217-2:2017. Furthermore, the DBP oil absorption of carbon black is preferably low. Specifically, 100 ml / 100 g or less is preferred. DBP oil absorption indicates the degree of development of the structure, which is a primary aggregation. Generally, the smaller the particle size of carbon black, the more aggregates tend to develop. The carbon black used in the present invention is preferably one with a structure that is not very developed compared to the particle size. It is believed that the presence of aggregates in small units allows for better light absorption. Furthermore, within the above range, the viscosity of the paint does not increase too much, resulting in good application properties.

[0014] Silica is used to provide the coating film with appropriate irregularities, and the silica content must be 16.0 to 28.0 parts by mass per 100 parts by mass of binder resin. Preferably, it is 19.5 to 22.5 parts by mass. If it is 16.0 parts by mass or more, the convex portions of the irregularities are sufficiently obtained, resulting in a low total reflection value. If it is 28.0 parts by mass or less, the concave portions of the irregularities can be secured in the coating film, resulting in a coating film with good irregularities. By ensuring that the amount is 19.5 parts by mass or more and 22.5 parts by mass or less, the viscosity of the paint does not increase too much, and good applicability can be obtained.

[0015] Silica has a specific surface area of ​​130m 2 / g or more 400m 2 / g or less, and further, the specific surface area is preferably 150 m 2 / g or more 400m 2When the surface roughness is in this range, it is easy to create appropriate unevenness, and the total reflection value can be kept low. The specific surface area of ​​silica is 150m 2 / g or less than 400m 2 If the specific surface area exceeds 1 / g, it may be difficult to reduce the total reflection value. When using such silica, it may be difficult to obtain a desirable roughness; for example, as shown in Figure 2, the surface may be buried in the binder resin, reducing the roughness and making it difficult to maintain a low total reflection value. Here, the specific surface area of ​​silica can be determined by a measurement method in accordance with JIS K6430:2008.

[0016] Furthermore, it is preferable that the silica have an oil absorption of 270 ml / 100 g or more. Silica also rarely exists as a single primary particle, but mostly as a secondary particle. The oil absorption here refers to the oil absorption of linseed oil, modeled after JIS K5101-13. If the oil absorption is high, the silica will have many voids inside the secondary particles, which means it will be bulky and will be prone to creating unevenness. By having an oil absorption of 270 ml / 100 g or more, sufficient unevenness can be achieved when the coating is made, and the total reflection value can be reduced.

[0017] The silica is preferably chain silica having a pore volume of 1.6 ml / g or more. Chain silica is wet silica produced by the gel process. The gel process is a production method in which the neutralization reaction of sodium silicate and inorganic acid proceeds through acidification, and the silica aggregates while suppressing the growth of primary particles, forming a three-dimensional network structure. Chain silica is more preferable because its secondary particles are strong and resistant to crumbling, making it easier to maintain its unevenness when processed into paints and coatings. Furthermore, the larger the pore volume, the more bulky the silica becomes, making it easier to create unevenness in the coating film. By having a pore volume of 1.6 ml or more, sufficient unevenness can be obtained when the coating film is made, and the total reflection value can be reduced. Furthermore, depending on the intended use, the surface anti-reflection coating may need to be able to handle light incident from various angles. If it is necessary to suppress the reflection of light from the side of the coating film, larger irregularities are required. Therefore, it is preferable for the coating film to contain large particles. The silica used in the present invention can be used in combination with silica having different average particle sizes. It is preferable to use silica having an average particle size of 8.0 μm or more and 15.0 μm, and more preferably to use silica having an average particle size of 2.0 μm or more but less than 8.0 μm. Silica has a large surface area and is excellent in adhesion to the binder resin, and is less likely to fall off due to the increased particle size of resin particles. By making the average particle size of silica (B) 8.0 μm or more, it is possible to reduce the reflection of light from the lateral direction, and by making it 15.0 μm or less, it is possible to prevent particles from falling off. Here, the average particle size of silica can be a value obtained by a laser analysis / scattering method in accordance with JIS Z8825:2013.

[0018] When silica (B) has an average particle size of 8.0 μm or more and 15.0 μm or less, the content of silica (B) is preferably 5% by mass or more and 30% by mass or less, and more preferably 10% by mass or more and 20% by mass or less, based on the total mass of the silica used in the present invention. By making the content of silica (B) 5% by mass or more, the effect on glossiness becomes more pronounced, and by making it 30% by mass or less, it is possible to improve the effect on glossiness while achieving a balance with total reflection. Reflection for light incident from the side can be evaluated by measuring specular gloss. Hereinafter, specular gloss will sometimes be simply referred to as gloss. The lower the specular gloss, the less reflection there is, and the more preferable it is. Specular gloss can be measured using the method described in JIS Z 8741:1997. Specifically, the coating surface was measured using a handheld glossmeter PG-IIM manufactured by Nippon Denshoku Industries Co., Ltd. Specifically, the gloss at 60° was measured using "Method 3" as specified in JIS, and if the gloss was 10 or less, the gloss at 85° was measured and evaluated using "Method 1," which is applicable to a gloss of 10 or less using "Method 3."

[0019] In this embodiment, the binder resin is not particularly limited. For example, resins such as acrylic resins, urethane resins, epoxy resins, alkyd resins, and polyester resins can be used. These binder resins can be used alone or in combination of two or more. Among them, two-component reactive acrylic resins are more preferred in terms of light resistance and adhesion to the substrate. Examples of two-component reaction type acrylic resins include copolymers of comonomers such as acrylic acid, acrylic esters, methacrylic acid, styrene, acrylamide, vinyltoluene, glycidyl methacrylate, and hydroxyethyl acrylate, and acrylic polyols copolymerized with acrylic esters and vinyl compounds are widely used because their properties can be easily adjusted. When using a two-component reactive acrylic resin, various curing agents can be used. For example, for acrylic polyol, isocyanate compounds such as aliphatic diisocyanates such as hexamethylene diisocyanate (HMDI) and trimethylhexamethylene diisocyanate (TMDI), alicyclic diisocyanates such as isophorone diisocyanate (IPDI), aromatic-aliphatic diisocyanates such as xylylene diisocyanate (XDI), aromatic diisocyanates such as tolylene diisocyanate (TDI) and 4,4-diphenylmethane diisocyanate (MDI), and hydrogenated diisocyanates such as dimer acid diisocyanate (DDI), hydrogenated TDI (HTDI), hydrogenated XDI (H6XDI), and hydrogenated MDI (H12MDI) can be used.

[0020] In this embodiment, the coating material for forming the coating film preferably further contains a solvent. The solvent is preferably an organic solvent from the viewpoint of the solubility of the binder resin. The coating material can be prepared by dispersing and diluting the binder resin, carbon black, silica, etc., with the organic solvent. The solvent may be any known solvent commonly used in paints. Specific examples of the solvent include the following: Chain hydrocarbons such as neopentane, n-hexane, n-heptane, and Solvesso; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as trichloroethylene and perchloroethylene; alcohols such as methanol, ethanol, isopropanol, and n-butanol; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; esters such as ethyl acetate and n-butyl acetate; ethers such as cellosolve, butylsolve, and cellosolve acetate; and mineral spirits (hydrocarbon oils). The above solvents may be used alone or in any combination of two or more in any ratio. For example, by mixing a plurality of solvents, the drying speed can be controlled. The dilution ratio can also be adjusted as desired depending on the application. For example, it can be adjusted appropriately depending on the application method, such as using an applicator, brush, or spray. By using the coating material of the present invention, it is possible to provide a surface antireflective coating material that can form a surface antireflective coating film with a low total reflectance without the risk of the contained particles falling off, even when using a conventionally known application method, such as using an applicator, brush, roller, roll coating, spray, or dip coating.

[0021] In this embodiment, other additives may be contained within a range that maintains the surface anti-reflection performance of the coating film to be formed. For example, additives such as pigments, resin particles, dispersants, leveling agents, thickeners, preservatives, and antifungal agents can be used alone or in combination. To adjust the viscosity of the coating, for example, thickeners such as bentonite, silicone elastomers, thickening polysaccharides, glycols, and diluting solvents may be used. In order to improve the adhesion of the resulting coating film to the substrate, in addition to the above-mentioned silane coupling agents, silicone-based coupling agents, aluminate coupling agents, titanate coupling agents, etc. may be used. To improve the leveling properties of the resulting coating film, leveling agents such as silicone oil and surfactants may be used. In order to improve the matte surface of the resulting coating film, resin particles, glass powder, quartz powder, mica powder, etc. may be used. To adjust the color tone of black, a dye, organic pigment, or inorganic pigment may be used as a complementary color. To improve the light resistance of the resulting coating film, examples of ultraviolet absorbers include benzophenone-based, salicylate-based, triazine-based, benzotriazole-based, zinc oxide fine particles, titanium oxide fine particles, and the like. Examples of the antiseptic and antifungal agent include benzimidazole-based, isothiazolyl-based, haloallylsulfone-based, iodopropargyl-based, benzothiazole-based, phenol-based, triazine-based, adamantane-based, and pyridine-based agents.

[0022] The total reflectance in the present invention is also called the total light reflectance, and if the total reflectance from 400 nm to 700 nm is 3.0% or less, it can be used as a surface anti-reflection coating film, preferably 2.4% or less, and more preferably 2.2% or less. The total reflectance is measured using a spectrophotometer (for example, trade name: V-670, manufactured by JASCO Corporation) equipped with an integrating sphere unit.

[0023] <Method of manufacturing anti-reflective coating> The surface antireflection coating material can be produced by mixing and dispersing a binder resin, carbon black or dye, resin particles, silica, and, if necessary, other materials such as a solvent. Dispersion of the mixed solution can be carried out by a known dispersion method, and for example, a ball mill, a paint shaker, a basket mill, a Dyno Mill, an Ultra Visco Mill, an annular type disperser, etc. can be used.

[0024] <Method of manufacturing surface anti-reflective coating film> The antireflective coating material of the present invention can be applied to a substrate, dried, and cured to form an antireflective coating film. The substrate can be any known substrate, such as glass, resin, or metal. The method for forming the coating film is not particularly limited, and known coating methods can be used. Examples of coating methods include application with an applicator, brush, roller, roll coating, spraying, and dip coating. Furthermore, the drying and curing methods can be selected depending on the application, such as hot air, far infrared rays, and natural drying. [Example]

[0025] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. The raw materials used in each of the examples and comparative examples are shown below.

[0026] [Binder resin] Coatax LH-601 (Toray Fine Chemicals Co., Ltd.) two-component curing acrylic polyol Acrydic A-817 (DIC Corporation) two-component curing acrylic polyol Duranol G4672 (Asahi Kasei) two-component curing polyol EP4100 (ADEKA) two-component curing epoxy resin [Curing agent] Burnock DN981 (DIC) isocyanurate curing agent jER Cure 113 (Mitsubishi Chemical Corporation) alicyclic amine curing agent 〔silica〕 Nipple AZ204 (Tosoh Silica Corporation) BET specific surface area 300m 2 / g, oil absorption 355ml / 100g, average particle size 2.9μm, gel method silica (pore volume 2.0ml / g) Nipple AZ200 (Tosoh Silica Corporation) BET specific surface area 300m 2 / g, oil absorption 330ml / 100g, average particle size 4.2μm, gel method silica (pore volume 2.0ml / g) Nipple AZ400 (Tosoh Silica Corporation) BET specific surface area 300m 2 / g, oil absorption 315ml / 100g, average particle size 7.1μm, gel method silica (pore volume 2.0ml / g) Nipgle AY200 (Tosoh Silica Corporation) BET specific surface area 300m 2 / g, oil absorption 280ml / 100g, average particle size 3.6μm, gel method silica (pore volume 1.6ml / g) Nipsil E220A (Tosoh Silica Corporation) BET specific surface area 150m 2 / g, oil absorption 350ml / 100g, average particle size 4.2μm, precipitated silica Nipsil SP200 (Tosoh Silica Corporation) BET specific surface area 198m 2 / g, precipitated silica ACEMATT OK412 (EVONIC) BET specific surface area 130m 2 / g, average particle size 6.3μm, precipitated silica Nipple AZ6A0 (Tosoh Silica Corporation) BET specific surface area 300m 2 / g, oil absorption 315ml / 100g, average particle size 9.3μm, gel method silica (pore volume 1.3ml / g) Nipgle AY8A2 (Tosoh Silica Corporation) BET specific surface area 350m 2 / g, oil absorption 250ml / 100g, average particle size 13.4μm, gel method silica (pore volume 1.4ml / g) Nipgle BY001 (Tosoh Silica Corporation) BET specific surface area 450m 2 / g, oil absorption 200ml / 100g, average particle size 14.3μm, gel method silica (pore volume 1.3ml / g) Nipple BZ400 (Tosoh Silica Corporation) BET specific surface area 450m 2 / g, oil absorption 315ml / 100g, average particle size 6.0μm, gel method silica (pore volume 1.8ml / g) Nipgle CX200 (Tosoh Silica Corporation) BET specific surface area 750m 2 / g, oil absorption 115ml / 100g, average particle size 2.2μm, gel method silica (pore volume 0.5ml / g) Nipgle BY200 (Tosoh Silica Corporation) BET specific surface area 450m2 / g, oil absorption 220ml / 100g, average particle size 2.6μm, gel method silica (pore volume 1.3ml / g) [Carbon black] RAVEN 5000UII (Columbian Chemical Co.) Nitrogen specific surface area 350m 2 / g, DBP oil absorption 95cm 3 / 100g Mitsubishi Carbon Black #2650 (Mitsubishi Chemical Corporation) Nitrogen specific surface area 370m 2 / g, DBP oil absorption 73cm 3 / 100g Mitsubishi Carbon Black #1000 (Mitsubishi Chemical Corporation) Nitrogen specific surface area 180m 2 / g, DBP oil absorption 56cm 3 / 100g Toka Black #5500 (manufactured by Tokai Carbon Co., Ltd.) Nitrogen specific surface area 225m 2 / g, DBP oil absorption 155cm 3 / 100g SUNBLACK 235 (Asahi Carbon Co., Ltd.) Nitrogen specific surface area 24m 2 / g, DBP oil absorption 49cm 3 / 100g 〔dye〕 OIL BLACK HBB (Orient Chemical Industries Co., Ltd.) VALIFAST BLACK 3820 (Orient Chemical Industries Co., Ltd.) [Resin particles] Daiamide WS200P (manufactured by Daicel-Evonik) polyamide (PA) resin particles (average particle diameter 80 μm) Bestsint 2157 (manufactured by Daicel-Evonik) polyamide (PA) resin particles (average particle diameter 50 μm)

[0027] <Preparation of surface anti-reflective coating> The materials were mixed in the ratios shown in Table 1 or Table 2 to obtain the surface anti-reflection coating materials of Examples 1 to 24 and Comparative Examples 1 to 10. The values ​​for each material listed in Table 1 or Table 2 are the number of parts per 100 parts by mass of the total solid content of the binder resin and curing agent. In addition, the numbers in parentheses for the binder and curing agent in the tables are the solid content amounts. Each material except the curing agent was weighed and dispersed in a paint shaker, and then the curing agent was stirred with a hand mixer to obtain a surface anti-reflection coating material. Details will be described later in Example 1.

[0028] <Creating a surface anti-reflection film> The surface antireflection coating material obtained by the above method was used with an applicator to obtain a surface antireflection film, the details of which will be described later in Example 1.

[0029] <Evaluation> The front-surface antireflection films prepared in the examples and comparative examples were evaluated as follows.

[0030] [Surface roughness] Surface roughness was measured using a non-contact laser measuring device. Specifically, surface data was measured using a color 3D laser microscope VK-8710 (manufactured by Keyence Corporation) with a 100x standard objective lens (CF IC EPI Plan 100X) at a measurement pitch of 0.2 μm. Roughness was calculated using the accompanying software VK-Analyzer (manufactured by Keyence Corporation). A straight line with a measurement length of 140 μm was extracted from the measured surface data, and Ra and Rlr were calculated under the conditions of no cutoff value λs and no cutoff value λc. The average values ​​of n = 3 were calculated and used as Ra and Rlr. [Film Thickness] The film thickness was measured with a micrometer. Specifically, the thickness of the PET film after coating and curing was measured at three locations using a Mitutoyo Coolant Proof Micrometer MDC-25MX, and the average value was calculated. The difference between the calculated value and the thickness of the uncoated PET film was taken as the film thickness of the coating.

[0031] [Total light reflectance measurement] The total light reflectance of the antireflective coating film obtained in the above Examples and Comparative Examples was measured using a spectrophotometer (product name: V-670, manufactured by JASCO Corporation) equipped with a 150 mmφ integrating sphere unit to evaluate the antireflective coating film in the visible light (400-700 nm) region. In the measurement, as shown in Figure 3, incident light 2 was incident on the front-surface anti-reflection coating 1 at a fixed angle of incidence 7 of 7° relative to the normal line 6 extending perpendicularly, with wavelengths ranging from 350 nm to 850 nm in 1 nm increments. Diffuse reflected light 5, including reflected light 3, was then measured. The measurement was performed three times on the same sample, and the average of the three measurement results obtained at wavelengths of 400 nm to 700 nm was calculated to determine the total light reflectance for visible light. The total light reflectance was evaluated as follows: AA: Total light reflectance for visible light is "2.2% or less." A: The total light reflectance for visible light is "more than 2.2% and 2.4% or less." B: The total light reflectance for visible light is "more than 2.4% and 3.0% or less." C: Total light reflectance for visible light is "more than 3.0%." [Specular gloss measurement] The gloss of the surface anti-reflective coating film was evaluated according to the method described in JIS Z 8741:1997. The surface of the surface anti-reflective coating film obtained in the above Examples and Comparative Examples was measured using a handheld gloss meter PG-IIM manufactured by Nippon Denshoku Industries Co., Ltd. When the gloss at 60° was measured using "Method 3" as specified in the JIS, it was found to be 10 or less. Therefore, the gloss at 85° was measured using "Method 1," which is within the applicable range for "Method 3" where a gloss of 10 or less is used. The measured gloss was evaluated as follows: AA: The gloss level at 85° is "1.5 or less." A: The gloss at 85° is "more than 1.5 and 3.0 or less." B: Glossiness at 85° exceeds 3.0.

[0032] [Tape removal] The tape peeling evaluation of the surface antireflective coating film was carried out as follows. Cellotape (registered trademark) No. 405 (manufactured by Nichiban Co., Ltd.) was placed on the surface antireflective coating film obtained in the above Examples and Comparative Examples, and an 18 mm x 18 mm area was rubbed with an eraser 15 times back and forth vertically and horizontally so that it adhered firmly. The Cellotape (registered trademark) No. 405 (manufactured by Nichiban Co., Ltd.) was then peeled off from the surface antireflective coating film, and the Cellotape (registered trademark) No. 405 (manufactured by Nichiban Co., Ltd.) was visually inspected for black spots on the Cellotape (registered trademark) No. 405 (manufactured by Nichiban Co., Ltd.) due to particle detachment from the coating film. The evaluation was carried out according to the following criteria. A: The sunspot is 0. B: There are 1 to 5 black spots. C: There are 5 or more sunspots.

[0033] [Overall Judgment] ◯: The total reflection was judged as AA to B, and the tape peeling was judged as A to B, with no C in either case. ×: Either the total reflection judgment or the tape peeling judgment had a C.

[0034] [Transmittance measurement] To evaluate the surface antireflection coating film in the visible light (400 to 700 nm) region, transmittance measurement was performed on the surface antireflection coating film obtained in the above Examples and Comparative Examples using a spectrophotometer (product name: V-670, manufactured by JASCO Corporation) equipped with a 150 mmφ integrating sphere unit. For the measurements, the anti-reflective coating was set in front of the entrance window of the integrating sphere unit, and as shown in Figure 3, incident light 2 was made incident on the anti-reflective coating 1 at a fixed angle of incidence 7 of 0° with respect to a normal line 6 extending perpendicularly to the coating 1, with wavelengths ranging from 350 nm to 850 nm in 1 nm increments. Measurements were then taken of the transmitted light 4. Measurements were taken three times for the same sample, and the average of the three measurement results obtained at wavelengths of 400 nm to 700 nm was calculated to determine the transmittance for visible light.

[0035] [Contact angle] The following measurements were carried out to evaluate the contact angle of the antireflective coating film. The contact angle was measured using a contact angle measuring device (trade name: DropMaster DM500, manufactured by Kyowa Interface Science Co., Ltd.) based on the sessile drop method for the antireflective coating films obtained in the above Examples and Comparative Examples. A 1.0 μL droplet of ion-exchanged water was created using a syringe, and the angle formed between the coating film and the droplet when it landed on the coating film surface was measured. The average of the three measurements obtained was calculated and used as the contact angle.

[0036] Example 1 <Preparation of surface anti-reflective coating> The following materials were weighed into a 100ml glass bottle to obtain a total of 50g: 180 parts by weight (90 parts by weight solids) of binder resin (Coatux LH-601), 22.3 parts by weight of carbon black (RAVEN 5000UII), 22.3 parts by weight of silica (Nipgel AZ204), and 156.7 parts by weight of thinner. The thinner was added so that the combined weight of the solvent in the binder resin solution and the solvent in the hardener solution (to be added later) was 250 parts by weight. 50g of glass beads (1.5mm diameter) for dispersion were added to the paint mixture, which was then dispersed in a paint shaker for 10 minutes. The mixture was then filtered through a nylon mesh (250µm mesh). 10 g of the filtered sample was taken, and 13.3 parts by mass (solid content 10 parts by mass) of a curing agent (Burnoc DN981) was added, followed by stirring with a hand mixer for 2 minutes to obtain the surface anti-reflection coating of Example 1. <Creating a surface anti-reflection film> The anti-reflective coating obtained by the above method was applied to a polyethylene terephthalate (PET) film using an applicator with a gap of 150 μm. After air drying for 5 minutes, the coating was cured at 100°C for 2 hours to obtain an anti-reflective coating. The thickness of the cured coating was 28 μm. (Examples 2 to 4, 44, and 45) A paint was prepared in the same manner as in Example 1, except that the binder resin, curing agent, and solvent in Example 1 were changed as shown in Table 1 or Table 3 and the amount of thinner was adjusted accordingly. A coating film was produced using the resulting paint in the same manner as in Example 1. The evaluation results are shown in Table 1 or Table 2. (Examples 5 to 13, Comparative Examples 7 to 10) A paint was prepared in the same manner as in Example 1, except that the blending amounts of carbon and silica in Example 1 were changed as shown in Table 1 or Table 3. Furthermore, a coating film was produced using the resulting paint in the same manner as in Example 1. The evaluation results are shown in Table 1 or Table 3. (Examples 14 to 16, Comparative Example 6) Paints were prepared in the same manner as in Example 1, except that the type of carbon in Example 1 was changed as shown in Table 1 or Table 3. Furthermore, coating films were produced using the resulting paints in the same manner as in Example 1. The evaluation results are shown in Table 1 or Table 3. (Examples 17 to 23, 26 to 34, Comparative Examples 1 and 2) Paints were prepared in the same manner as in Example 1, except that the type of silica in Example 1 was changed as shown in Table 1, Table 2, or Table 3. Coating films were produced using the resulting paints in the same manner as in Example 1. The evaluation results are shown in Table 1, Table 2, or Table 3. Example 24 The paint of Example 1 was applied to a PET film using a brush. After air drying for 5 minutes, it was cured at 100°C for 2 hours to obtain a front-surface anti-reflection film. The evaluation results are shown in Table 2. Example 25 Using the paint of Example 1 as a base, butyl acetate was further added to adjust the viscosity of the paint to be suitable for spraying. The resulting paint was applied four times to a PET film using an RG-3L-3 hand spray gun manufactured by Anest Iwata Corporation. After air drying for 10 minutes, the paint was cured at 100°C for 2 hours to obtain a front-surface anti-reflective coating. The evaluation results are shown in Table 2. Examples 35 to 40 Paints were prepared in the same manner as in Example 1, except that the type and amount of silica in Example 1 were changed as shown in Table 2 or Table 3. Coating films were produced using the resulting paints in the same manner as in Example 1. The evaluation results are shown in Table 2 or Table 3. (Examples 41 to 43) Based on the paints of Examples 32, 27, and 31, butyl acetate was further added to adjust the viscosity of the paints to be suitable for spraying. Using the resulting paints, coating films were produced in the same manner as in Example 25. The evaluation results are shown in Table 3. (Comparative Examples 3 and 4) Paints were prepared in the same manner as in Example 1, except that dyes were blended as shown in Table 2 instead of the carbon used in Example 1. Furthermore, coating films were produced using the resulting paints in the same manner as in Example 1. The evaluation results are shown in Table 3. (Comparative Example 5) A paint was prepared in the same manner as in Example 1, using the materials of Example 1 and further adding roughening particles: 25 parts by mass of Vestsint 2157 and 25 parts by mass of Daiamide WS200P. A coating film was produced using the resulting paint in the same manner as in Example 1. The evaluation results are shown in Table 3.

[0037] [Table 1]

[0038] [Table 2]

[0039] [Table 3]

[0040] The present invention is not limited to the above-described embodiments, and various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, the following claims are appended to apprise the public of the scope of the present invention.

[0041] This application claims priority based on Japanese Patent Application No. 2023-192357, filed November 10, 2023, the entire contents of which are incorporated herein by reference. [Explanation of symbols]

[0042] 1 Surface anti-reflection coating 2 Incident light 3 Reflected light 4 Transmitted light 5 Diffuse 6 Normals 7 Angle of incidence

Claims

1. A surface anti-reflective coating film containing a binder resin, carbon black, and silica, the arithmetic mean roughness (Ra) of the front-surface antireflection coating film is 0.3 μm or more and 3.0 μm or less, and the developed length ratio (Rlr) is 1.6 or more; The specific surface area of ​​the carbon black is 175 m ２ / g or more 400m ２ / g or less, the content of the carbon black is 2.5 parts by mass or more and 28.0 parts by mass or less with respect to 100 parts by mass of the binder resin, The silica includes silica (A) and silica (B), The average particle size of the silica (A) is 2.0 μm or more and less than 8.0 μm, The average particle size of the silica (B) is 8.0 μm or more and 15.0 μm or less, the specific surface area of ​​the silica (A) is 130 m 2 / g or more and 400 m 2 / g or less; the specific surface area of ​​the silica (B) is 300 m 2 / g or more and 400 m 2 / g or less; the content of the silica is 16.0 parts by mass or more and 28.0 parts by mass or less with respect to 100 parts by mass of the binder resin, A front surface anti-reflective coating film, characterized in that the content of the silica (B) is 5 mass % or more and 30 mass % or less with respect to the total mass of the silica.

2. The specific surface area of ​​the silica (A) is 130 m ２ / g or more 300m ２ The front surface antireflective coating film according to claim 1, wherein the surface antireflective coating film has a viscosity of 1 / g or less.

3. 3. The front-surface antireflective coating film according to claim 2, wherein the oil absorption of the silica (A) is 280 ml / 100 g or more and 355 ml / 100 g or less.

4. 4. The front surface antireflective coating film according to claim 3, wherein the silica (A) is chain silica, and the pore volume of the silica (A) is 1.6 ml / g or more and 2.0 ml / g or less.

5. 2. The front-surface antireflective coating film according to claim 1, wherein the total reflectance of the front-surface antireflective coating film in the range of 400 nm to 700 nm is 2.4% or less.

6. An optical member having the surface antireflection coating film according to any one of claims 1 to 5.

7. A surface anti-reflective coating containing a binder resin, carbon black, and silica, The specific surface area of ​​the carbon black is 175 m ２ / g or more 400m ２ / g or less, the content of the carbon black is 2.5 parts by mass or more and 28.0 parts by mass or less with respect to 100 parts by mass of the binder resin, The silica includes silica (A) and silica (B), The average particle size of the silica (A) is 2.0 μm or more and less than 8.0 μm, The average particle size of the silica (B) is 8.0 μm or more and 15.0 μm or less, The specific surface area of ​​the silica (A) is 130 m ２ / g or more 400m ２ / g or less, the specific surface area of ​​the silica (B) is 300 m 2 / g or more and 400 m 2 / g or less; the content of the silica is 16.0 parts by mass or more and 28.0 parts by mass or less with respect to 100 parts by mass of the binder resin; The content of the silica (B) is 5% by mass or more and 30% by mass or less based on the total mass of the silica. Surface anti-reflective paint.

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