Coating material, film, and method for producing member having film

Abstract

A coating material has fibers 31, particles 32, a resin, and a solvent. Each fiber 31 has protrusions 312 on the peripheral edge and recesses 311 recessed more toward the axial center than the protrusions 312. The particles 32 adhere to each fiber 31, and the number of particles 32 adhering to the recesses 311 is greater than the number of particles 32 adhering to the protrusions 312.

Description

Method for manufacturing a paint, a film, and a member having the film

[0001] The present disclosure relates to a paint and a film containing a fiber having a convex portion and a concave portion at a periphery and a resin, and a method for manufacturing a member having the film. The present disclosure also relates to an optical member, an optical device, an imaging device, etc. using the film for optical applications.

[0002] A paint containing a fiber having a convex portion and a concave portion at a periphery and a resin is known. By forming a film from this paint, improvement in functions of an article to which it is applied, such as optical performance and design of an optical member, can be expected. Patent Document 1 discloses using the film as an antireflection film.

[0003] An optical device such as a lens barrel has a housing and an optical system including a plurality of lenses or mirrors provided in the housing. Light rays incident on the optical device mainly enter the lenses, and the light rays are imaged to form an image. On the other hand, there are also light rays that are not imaged and do not contribute to the formation of the subject image. Since the light rays that do not contribute to the formation of the subject image are incident from disordered directions, they are incident not only on optical members such as lenses but also on other parts inside the housing, becoming a factor for generating unnecessary reflected light and scattered light. These lights are called stray light. When the stray light reaches the imaging element, flare and ghost are generated, and an antireflection film is known as a means for suppressing this stray light.

[0004] Japanese Patent Application Laid-Open No. 2020-008843

[0005] However, when the resin enters the concave portion of the fiber, there is a risk that the above-described functions may not be exhibited, and means for making it difficult for the resin to enter the concave portion of the fiber have been demanded.

[0006] A first embodiment for solving the above problems is a paint having a fiber, particles, a resin, and a solvent, wherein the fiber has a convex portion at a periphery and a concave portion that is recessed toward the axial center from the convex portion, the particles are attached to the fiber, and the amount of the particles attached to the concave portion is larger than the amount of the particles attached to the convex portion.

[0007] A second embodiment for solving the above problems is a film comprising a resin layer made of resin, fibers protruding from the resin layer, and particles, wherein the fibers have convex portions at their periphery and concave portions that are recessed toward the axial center from the convex portions, and the particles are attached to the fibers, and the number of particles attached to the concave portions is greater than the number of particles attached to the convex portions.

[0008] A third embodiment for solving the above problems is a method for manufacturing a paint, characterized by comprising the steps of: mixing a fiber having a convex portion on its periphery and a concave portion that is recessed toward the axial center from the convex portion, particles and / or particle precursors, and an aqueous solvent to obtain a mixed solution; drying the mixed solution to obtain a fiber to which the particles and / or particle precursors are attached to the convex portion and the concave portion; and mixing the fiber to which the particles and / or particle precursors are attached, a resin, and a solvent.

[0009] This disclosure provides a coating and film in which resin does not easily penetrate into the recesses of fibers, and a method for manufacturing the film. Furthermore, this disclosure provides optical components, optical instruments, and imaging devices, etc., using the film for optical applications.

[0010] Schematic diagram of the component of this disclosure. Side perspective view of the fiber. Side perspective view of the fiber. Front cross-sectional view of the fiber. Front cross-sectional view of the fiber. Front cross-sectional view of the fiber. Front cross-sectional view of the fiber. Front cross-sectional view of the fiber. Front cross-sectional view of the fiber. Front cross-sectional view of the fiber. Front cross-sectional view of the fiber. Schematic diagram of the spray can of this disclosure. Schematic diagram of the imaging device of this disclosure. Schematic diagram of the display device of this disclosure. Schematic diagram of the building material of this disclosure. Schematic diagram of the clothing of this disclosure. Schematic diagram of the camera mounting device of this disclosure.

[0011] Patent Document 1 discloses a method for suppressing the reflection of obliquely incident light, which is prone to reflection and scattering, by coating the surface of a substrate with a black paint containing irregularly shaped fibers having protrusions, thereby forming a structure (fiber structure) in which the tips of the protrusions of the irregularly shaped fibers protrude into the air. To suppress the reflection of obliquely incident light, it is effective to form a structure with thickness and voids to confine the light inside. However, the surface area increases due to the formation of the structure, which increases surface reflection. For example, a structure formed by multiple fibers can confine obliquely incident light inside, but it may strongly reflect perpendicularly incident light.

[0012] The inventors' investigations revealed the following: The resin components in the resin layer, which forms the base (matrix) of the film, and the resin components that function as binders to bind the fibers together, reflect light more easily than structures formed by fibers and voids because their surfaces are smooth. Furthermore, the resin components tend to adhere to the depressions in the uneven structure of the fibers, often smoothing out the uneven structure. This is because capillary forces act in the depressions, causing the resin components or liquids such as resin components containing solvents to remain once they enter, and then dry, leaving the resin components behind.

[0013] Further investigations by the inventors revealed that attaching particles to the recesses of fibers having an uneven surface around their edges results in high anti-reflective performance not only for obliquely incident light but also for perpendicularly incident light. The inventors believe this is because the attachment of particles weakens the capillary forces acting on the recesses, making it easier for the resin component or solvent-containing resin to flow out to the convex or resin layer side after application to the substrate, thereby suppressing surface reflection of the fiber structure. It was also found that the fewer particles attached to the convex parts compared to the recesses, the weaker the capillary forces acting on the recesses become. The inventors believe this is because the difference in interfacial tension between the fiber surface and the resin at the boundary between the recesses and convex parts increases.

[0014] Therefore, the paint and film of this disclosure employ a configuration in which the particles adhering to the recesses of the fibers are greater than the particles adhering to the protrusions.

[0015] [Embodiment 1] <Optical Member> The member using the film of this disclosure is a member having at least one of the following functions: optical properties, antifouling properties, antibacterial properties, antiviral properties, abrasion resistance, and design properties. First, the optical member will be described.

[0016] Figure 1 is a schematic cross-sectional view of an optical member according to Embodiment 1, cut from the stacking direction. The member 100 of this disclosure comprises a film 10 including a resin layer 2 and a fiber layer 3. In Figure 1, the film 10 is provided on a substrate 1, and the resin layer 2 of the film 10 is provided on the surface 1A of the substrate 1. Fibers 31 protrude from the surface 2A of the resin layer 2. Multiple fibers 31 are bound to each other using a resin 22, which has the same components as the resin constituting the resin layer 2, as a binder, and the gaps formed by the binding of the multiple fibers 31 are voids 24.

[0017] To explain Figure 1 from a different perspective, it can be said that the multiple fibers 3 are bonded to each other to form a fiber structure 30. The fiber structure 30 has a portion that is included in the resin layer 2 and a portion that is not included in the resin layer 2. The fiber layer 3 includes the portion of the fiber structure 30 that is not included in the resin layer 2 and protrudes, forming a void 24. The fiber structure 30 does not necessarily need to be bound with a binder; it may also be formed by intertwining, wrapping, etc., with each other. Furthermore, the film of this disclosure does not necessarily need to be formed over the entire surface 1A of the member 100; for example, it may be formed in a minute area of ​​1 mm square that is a part of the surface 1A.

[0018] (Substrate) The substrate 1 has a surface 1A of the substrate and a surface 1B which is the back surface of the substrate, opposite to the surface 1A of the substrate. A film 10, which is an anti-reflective film, is provided on the surface 1A of the substrate, in close contact with the surface 1A of the substrate. To increase the adhesion between the surface 1A of the substrate and the film 10, a primer layer may be provided on the surface 1A of the substrate. Examples of components constituting the primer layer include epoxy resin, urethane resin, acrylic resin, silicone resin, and fluororesin. The thickness of the primer layer is preferably in the range of 2 μm to 30 μm. If it is too thin, the adhesion may be insufficient, and if it is too thick, assembly may become difficult. In addition, the surface roughness of the surface 1A of the substrate may be increased to improve adhesion with the film 10.

[0019] The material of the base material 1 is not particularly limited, and metals or resins can be used. Examples of metals include aluminum, aluminum alloys, titanium, titanium alloys, stainless steel, magnesium, and magnesium alloys. From the viewpoint of cost and durability, aluminum alloys or magnesium alloys are preferred. Examples of resins include strong ones such as polycarbonate resin, acrylic resin, ABS resin, fluororesin, and PBT resin. Other resins include synthetic rubbers such as silicone rubber, butadiene rubber, and acrylonitrile rubber, as well as flexible ones such as natural rubber. Because the fiber structure 30 contains voids 24, it is easy to obtain strength and flexibility, and it can be suitably used as a high-strength or highly flexible component when combined with the above base material.

[0020] (Anti-reflective coating) The anti-reflective coating, film 10, includes a resin layer 2 made of resin and fibers 3 protruding from the resin layer 2. The anti-reflective performance is particularly suitable for visible light with wavelengths of 300 nm to 780 nm, but is not limited to that range, and functions similarly for near-infrared light with wavelengths of 780 nm to 2500 nm. The thickness (T2 + T3) of the film 10 is preferably in the range of 30 μm to 400 μm. Higher anti-reflective performance is achieved within this range. If it is less than 30 μm, the light confinement effect for obliquely incident light may be insufficient depending on the usage environment. If it exceeds 400 μm, depending on the manufacturing conditions, assembly of the coated article may become difficult. The anti-reflective coating may be subjected to post-processing. Further materials may be coated, for example, a low refractive index material such as resin or silica may be coated to slow down the change in refractive index of the medium incident on the fibers 3 from the air, thereby adding a function to prevent surface reflection. Furthermore, surface modification processing may be applied. Roughening the surface makes it easier to trap incident light. Examples include blasting, UV ozone irradiation, flame treatment, plasma etching, and plasma surface treatment. Blasting can provide an even greater anti-reflective effect by physically roughening the surface, regardless of the material of the fiber 3. Plasma surface treatment can further enhance the light trapping effect by creating a nano-sized uneven structure on the surface of the polymer material fiber 3. The effect depends on the material of the fiber 3, but polyester is particularly preferable.

[0021] [Resin layer] The resin layer 2 supports the fiber structure 30 and also plays a role in bringing the base material 1 and the fiber structure 30 into close contact.

[0022] The resin constituting the resin layer 2 is the cured product of the resin composition. The type of resin is not particularly limited and may be a single resin or a mixture. Examples of usable resins include acrylic resins, polyester resins, alkyd resins, fluororesins, epoxy resins, polyurethane resins, and polyether resins. Copolymers of each resin may also be used, but acrylic urethane resin is preferred due to its high adhesion to resin substrates and metal substrates.

[0023] The resin layer 2 may contain the fibers 31 included in the fiber layer 3. The fibers 31 included in the resin layer 2 will be explained in the section on the fiber layer.

[0024] The thickness T2 of the resin layer 2 is preferably in the range of 1 μm to 100 μm, and more preferably in the range of 20 μm to 80 μm. If T2 is too thin, the fibers 31 may detach from the film 10 depending on the usage environment. On the other hand, if it is too thick, the film thickness of the film 10 will be large, which may make it difficult to assemble the painted article depending on the manufacturing conditions.

[0025] [Fiber layer] The fiber layer 3 has a three-dimensional and complex uneven shape and is responsible for trapping incident light and scattering and absorbing it in the recesses 311 of the fiber 31.

[0026] The fiber layer 3 includes portions of the fiber 31 that are not included in the resin layer 2 of the fiber structure 30 and protrude from the surface 2A of the resin layer 2. In addition, voids 24, which are gaps between multiple fibers 31, are formed. Figures 2A and 2B are side perspective views of the fiber 31, and Figures 3A to 3H are front cross-sectional views of the fiber 31 cut by a plane perpendicular to the stretching direction, which is the fiber axis direction.

[0027] The thickness T3 of the fiber layer 3 is preferably in the range of 30 μm to 300 μm. Higher anti-reflective performance is achieved within this range. If it is less than 30 μm, the light confinement effect against obliquely incident light may be insufficient depending on the usage environment. If it exceeds 300 μm, depending on the manufacturing conditions, the fibers 31 may become prone to bending or assembly of painted articles may become difficult. The thickness T3 of the fiber layer 3 is the length of the fibers 31 protruding from the resin layer 2, and is the longest distance from the resin layer 2 to the tip of the fiber 31 in the +Z direction in Figure 1. It can be measured using a three-dimensional shape measuring machine (product name VR-3200, manufactured by Keyence), a laser microscope, a confocal microscope, or other known height measuring devices.

[0028] {Fiber} The fiber 31 has a convex portion 312 and a concave portion 311 that is recessed toward the axis center from the convex portion 312. The periphery is the outermost part when a cross section perpendicular to the axial direction of the fiber is cut out. The axis center is the centroid of that perpendicular cross section, and when the periphery is inscribed in a figure selected from a circle, ellipse, or polygon (inscribed by the dashed lines in Figures 3A to 3H), it is the center of that figure. Also, unless otherwise specified, the cross section refers to a cross section perpendicular to the axial direction of the fiber.

[0029] To absorb the light diffused within the recesses 311 and prevent reflected light from escaping, the material of the fiber 31 and the material of the recesses 311 are preferably light absorbers, and more preferably black. The number of recesses per fiber cross-section may be one or more, and the number may vary depending on the cutting position relative to the axial direction of the fiber, but to more efficiently confine light and prevent reflection, three or more are preferable, and five or more are preferable. Also, to ensure the strength of the fiber, 16 or fewer are preferable, and 12 or fewer are preferable. The recesses 311 may be continuous in the length direction of the fiber, or they may be scattered in a hole-like manner. The method of forming the recesses is not particularly limited, and one example is to extrude a molten resin solution using a fiber mold or die having an uneven shape and spin it. In this case, a fiber with continuous recesses formed as shown in Figure 2A will be formed. Alternatively, for example, soluble particles can be kneaded and spun, and then the particles can be removed by a dissolution treatment to form the recesses 311. Alternatively, for example, a fiber without an uneven shape can be subjected to an alkali weight reduction treatment to form the recesses 311. In these cases, the recesses 311 tend to form in a scattered manner, resulting in a side view as shown in Figure 2B and a cross-section as shown in Figure 3C. The shape of the fibers 31 can be observed using an optical microscope or a transmission electron microscope. The cross-sectional shape can be observed using the above methods after exposing the cross-section with a cutter, microtome, or cross-polisher.

[0030] The interior of the fiber 31 may be solid or hollow, but it is preferable that it be hollow. Figures 3D and 3E show examples of cross-sections of hollow fibers. When hollow, the specific gravity of the fiber 31 is lower, making it less likely to settle in the paint, which is the raw material for the film 10, thus improving storage stability. It is even more preferable that it is hollow and that the ends are closed. In other words, it is preferable that the end face of the fiber is formed as a continuous surface without voids. When the fiber 31 comes into contact with the substrate 1 during painting, it tilts according to the inversion moment, but if the ends are closed, the hollow part is not filled with paint components, so the mass is small, the inversion moment is small, and it is less likely to tilt. For this reason, even if the fiber content is small, the fiber structure 30 can be formed thickly, thus improving the anti-reflective performance.

[0031] It is preferable that the fibers 31 are bound to each other using resin 22, which has the same components as the resin that constitutes the resin layer 2, as a binder. This is because it increases the mechanical strength of the fiber structure 30. That is, it is preferable that at least a portion of the fibers 31 are covered with resin 22. The content of resin components attached to the fibers 31 in the fiber layer 3 is preferably 50 parts by mass or less, and more preferably 30 parts by mass or less, per 100 parts by mass of the fiber layer 3. If particles are attached to the fibers 31, the resin is more likely to flow off when the coating film dries, and the amount of resin in the fiber layer 3 can be reduced. Since the resin in the fiber layer easily reflects incident light, reducing the amount of resin is advantageous for the anti-reflective function. As the fiber density of the fiber structure increases, the resin components cling to the fibers in a way that crosslinks the fibers, so the ratio of resin components tends to increase. A method for measuring the resin content is, for example, the TG-DTA method. The fiber layer 3 is scraped off from the film 10, and the heat weight loss of the scraped fiber layer 3 is measured. At a temperature where fiber decomposition has not yet begun and the resin is not thermally decomposed or burned, the resin content in the fiber layer 3 can be determined by dividing the weight loss of the scraped fiber layer 3 by the weight of the fiber layer 3 before measurement and multiplying by 100. Alternatively, the resin content can be measured using a surface analysis device such as TOF-SIMS.

[0032] The fiber content 31 is preferably 5 parts by mass or more and less than 60 parts by mass, and more preferably 5 parts by mass or more and less than 33 parts by mass, per 100 parts by mass of the film. If the content is too low, the density of the fiber 31 decreases, and depending on the usage environment, the anti-reflective function may not be sufficient. On the other hand, if the content is too high, depending on the manufacturing method, the volume ratio of fibers in the fiber structure increases, and the volume of the voids that trap light decreases, which may increase the reflectivity on the surface of the fiber structure. Also, because the film thickness (T2 + T3) of the film 10 increases, depending on the manufacturing method, it may become difficult to assemble the painted article. In addition, because the ratio of fibers to resin components is high, the fibers may easily fall off the film 10. Furthermore, the fiber layer 3 may contain not only fibers 31 having convex portions 312 at the periphery and concave portions 311 that are recessed toward the axial center from the convex portions 312, but also other fibers. The fiber content 31 per 100 parts by mass of the total amount of fibers is preferably 20 parts by mass or more, and more preferably 50 parts by mass or more. More preferably, the amount is 80 parts by mass or more, and most preferably 100 parts by mass.

[0033] The width S of the fiber recess is preferably in the range of 0.5 μm to 30 μm. In the case of the fiber 31 in Figure 2A, the width S can be rephrased as the distance between adjacent protrusions 312. The width S is more preferably in the range of 5 μm to 15 μm. If the width S is less than 0.5 μm, depending on the usage environment, less light may enter the recess 311, and the anti-reflective function due to light confinement may be insufficient. On the other hand, if the width S is greater than 30 μm, depending on the usage environment, light may be reflected in the same way as on a flat surface, and the anti-reflective function may be insufficient.

[0034] The fibers are preferably short fibers. The fiber length L is preferably in the range of 1 μm to 1000 μm, and more preferably 400 μm or less. If it is too long, it may easily cause clogging depending on the performance of the painting equipment such as spray paint. In other words, if spray painting is used, it is more preferable that it be 400 μm or less. On the other hand, if it is too short, the thickness of the fiber structure 30 that traps light when the film 10 is formed may be small, which may result in insufficient anti-reflective function due to the light trapping effect. Methods for adjusting the length include crushing or cutting the long fibers, but cutting is preferred. For example, disc cutters, rotary cutters, and guillotine cutters can be used for cutting. Cutting the long fibers with a cutter while feeding them on a conveyor is preferred from the viewpoint of mass production, and a method of continuously cutting using a guillotine cutter and a belt conveyor is more preferred. When hollow fibers are used, it is particularly preferable because the frictional heat from the guillotine cutter is transferred to the cut surface, causing the fiber cross-section to plasticize and making it easier to close the ends. A preferred lower limit is 50 μm or more, and more preferably 100 μm or more.

[0035] The fiber thickness T is preferably in the range of 0.1 μm to 100 μm, and more preferably in the range of 1 μm to 50 μm. Fiber thickness refers to the maximum length when cut by a plane perpendicular to the fiber axis. If the fiber is thicker than this, the density of the fiber structure on the coating film increases, and depending on the usage environment, light may not be able to enter the fiber structure, potentially increasing surface reflection. On the other hand, if the fiber is thinner than this, depending on the usage environment, incident light may pass through, potentially resulting in insufficient anti-reflective function.

[0036] The aspect ratio (L / T) of a fiber is the ratio of its length L to its thickness T, and is preferably in the range of 5 to 500. The larger the aspect ratio, the easier the fibers become to intertwine and form a fibrous structure. If the aspect ratio is too high, the fibers may bend due to their own specific gravity, depending on the environment in which they are used.

[0037] The material of the fiber is not particularly limited, and polyamide, polyester, acrylic, polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyurethane, polycarbonate, aramid, rayon, cotton, wool, etc., can be used. Among these, synthetic polymers such as polyamide, polyester, acrylic, and aramid are preferred due to the ease with which they can form uneven shapes. Polyester, such as polyethylene terephthalate, is more preferred, as it has high strength and can form an anti-reflective film from which short fibers do not easily fall off. Furthermore, when hollow fibers are used, using a thermoplastic resin makes it easier to close the ends. Examples of thermoplastic resins include polyamide, polyester, acrylic, aramid, polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyurethane, and polycarbonate. Among these, polyester, such as polyethylene terephthalate, is more preferred from the viewpoint of strength. It is also preferable that the fiber be black in order to enhance the anti-reflective effect of visible light. The fiber may be a dope-dyed short fiber in which a black pigment such as carbon black is kneaded into the yarn before spinning, or a short fiber dyed with a dye, but from the viewpoint of anti-reflective properties, dope-dyed short fibers are preferred, and it is preferable that the entire surface, including the cross-section and recesses, is black. In other words, it is preferable that the fiber 31 is a black dope-dyed yarn.

[0038] {Particles attached to the fibers} Particles are attached to the protrusions 312 and recesses 311 of the fiber 31. The particles may include first particles 32 and second particles 33. There are more particles attached to the recesses 311 than to the protrusions 312. As a result, the capillary force acting on the recesses 311 is weakened by the attachment of particles, and after application to the substrate, the resin component or the resin containing the solvent flows out more easily to the protrusions 312 or the resin layer 2 side. Therefore, the film 10 obtained after drying has suppressed surface reflection of the fiber structure 30 (fiber layer 3). As a result, the film 10 can obtain high anti-reflective performance not only for obliquely incident light but also for perpendicularly incident light. The relationship between the amount of particles attached to the recesses 311 and the amount of particles attached to the protrusions 312 can be determined, for example, from images acquired with an optical microscope or a transmission electron microscope. The coverage rate can be calculated and compared from the area of ​​particles attached to the area of ​​the recesses 311 and the area of ​​particles attached to the area of ​​the protrusions 312. Furthermore, for example, after identifying the composition of the particles, the amount of elements present per unit surface area of ​​the recesses and protrusions can be determined and identified by energy-dispersive X-ray spectroscopy (SEM-EDX). The latter method allows for identification even when the apparent coverage is the same but the elemental ratios differ. Also, since the step of identifying the constituent elements of the particles is taken, the relative sizes of the particles can be determined even when there are multiple types of particles. The particles are effective even if they only partially cover the surface, but it is preferable that the coverage of the recesses 311 be 20% or more, and more preferably 35% or more. The coverage of the protrusions 312 should be lower than the coverage of the recesses 311.

[0039] While known methods may be used to attach the particles to the fiber 31, it is preferable to mix a fiber having a convex portion on its periphery and a concave portion that is recessed toward the axial center from the convex portion, particles and / or particle precursors, and a solvent, and then dry the mixture. When the mixture is dried, the solvent gradually evaporates, but the rate of evaporation differs between the fiber concave portion and the fiber convex portion. The convex portion has a large volatilization space, so the vapor pressure is low and evaporation is fast. On the other hand, the concave portion has a narrow volatilization space, so the vapor pressure is high and evaporation is slow. Also, because the solvent has surface tension, it flows into the concave portion. Due to this difference in evaporation rate and the surface tension of the solvent, as the drying process progresses, the solvent accumulates in the concave portion while increasing the concentration of particles, so that when drying is complete, a fiber with particles concentrated in the concave portion is obtained. For the above reasons, a solvent with high surface tension is preferable. Preferably it is 40 mN / m or more, and more preferably 60 mN / m or more. As the solvent to be used, a mixed solvent containing water or an aqueous solvent is preferred, and most preferably pure water.

[0040] The particles may be organic or inorganic. Examples of organic particles include colorants such as disperse dyes and pigments, and functional polymers such as light absorbers and conductive polymers. Among functional particles, inorganic particles such as conductive additives, insulating materials, or matting agents are preferred. Conductive additives and insulating materials are used to control the chargeability of the anti-reflective film and prevent the adhesion of dust, etc., so it is preferable that the particles include inorganic particles. For example, conductive additives, which are examples of the first particle 32, include aluminum, zirconium, zinc, magnesium and their hydroxides, carbon nanotubes, graphene, conductive carbon black, and tin-doped indium oxide (ITO). Among these, hydroxyaluminum colloids such as metaaluminic acid and aluminum hydroxide, and magnesium hydroxide are more preferred. Furthermore, when the particle adhesion treatment is performed in an aqueous solvent, acidic colloids of metal oxides having OH groups on the surface are also effective from the viewpoint of water dispersibility, and alumina sol is particularly preferred. Examples of insulating materials include oxides of aluminum, zirconium, zinc, and magnesium. Examples of matting agents, which are the second particle 33, can improve the anti-reflective effect and include silica (silicon oxide), porous silica (silicon oxide), titania, porous titania, calcium carbonate, talc, mica, zinc oxide, and cerium oxide. Among these, matting agents made of porous materials are particularly suitable for anti-reflective properties. Furthermore, when performing aqueous treatment, an acidic solution is preferable from the viewpoint of water dispersibility. Particles suitable for aqueous treatment as described above are more preferable because their high hydrophilicity results in low affinity to solvents and reduces capillary action on the resin in solvent-based paints. On the other hand, when performing solvent-based treatment, particles without hydrophilic groups such as OH groups or COOH groups are effective from the viewpoint of solvent dispersibility and are more preferable because they can similarly reduce capillary action on the resin in water-based paints. Silica particles that partially have OH groups and oxide particles such as alumina sol are often amphiphilic and exhibit a certain effect in both water-based and solvent-based paints, but they can be used more preferably in solvent-based paints.

[0041] The particle size of the particles is preferably smaller than the width S of the concave portion 311. Further, it is preferably 3 μm or less, more preferably 1 μm or less. When it is 3 μm or less, the reflected light can be diffused into the concave portion by Mie scattering. When it is 1 μm or less, Rayleigh scattering occurs and the scattering becomes stronger, improving the antireflection performance.

[0042] As described above, in the first embodiment, in the fiber having concave and convex portions included in the film provided on the member, more particles adhere to the concave portion of the fiber than to the convex portion. Therefore, the capillary force acting on the concave portion due to the adhesion of the particles is weakened, and after coating on the base material, the resin containing the resin component or the solvent easily flows out to the convex portion or the resin layer side. Therefore, the surface reflection in the fiber structure (fiber layer) of the dried film is suppressed. As a result, the film exhibits high antireflection performance not only for obliquely incident light but also for perpendicularly incident light.

[0043] [Embodiment 2] <Antireflection paint> The paint of the present disclosure is a paint having fibers, particles, a resin, and a solvent, and is a raw material (precursor) of the film 10 described above. The film 10 of the first embodiment can be obtained by drying the paint.

[0044] (Fibers) It is the same as the fiber described in the {fiber} section of Embodiment 1. The fiber 31 has a convex portion 312 at the periphery and a concave portion 311 that is recessed toward the axial center from the convex portion 312.

[0045] The fiber content 31 is preferably 5 parts by mass or more and less than 60 parts by mass, and more preferably 5 parts by mass or more and less than 33 parts by mass, per 100 parts by mass of paint solids. If the content is too low, the density of the fiber 31 decreases, and depending on the usage environment, the anti-reflective function of the film 10 may not be sufficient. On the other hand, if the content is too high, depending on the manufacturing method, the volume ratio of fibers in the fiber structure increases, and the volume of the voids that trap light decreases, which may increase the reflectivity on the surface of the fiber structure. In addition, the film thickness (T2 + T3) of the film 10 increases, which may make it difficult to assemble the painted article depending on the manufacturing method. Also, because the ratio of fibers to resin components is high, the fibers may easily fall off the film 10. Furthermore, the fibers may include not only fibers 31 having convex portions 312 and concave portions 311 that are recessed toward the axial center from the convex portions 312 at the periphery, but also other fibers. The fiber content 31 per 100 parts by mass is preferably 20 parts by mass or more, and more preferably 50 parts by mass or more. More preferably, the amount is 80 parts by mass or more, and most preferably 100 parts by mass.

[0046] (Particles) The particles are the same as those described in the section {Particles attached to the fibers} of Embodiment 1. The particles may include first particles 32 and second particles 33. There are more particles attached to the recesses 311 than to the protrusions 312. As a result, the capillary force acting on the recesses 311 is weakened by the attachment of the particles, and after application to the substrate, the resin component or the resin containing the solvent flows out more easily to the protrusions 312 or the resin layer 2 side. Therefore, the surface reflection of the fiber structure 30 (fiber layer 3) is suppressed in the dried film 10. As a result, the film 10 can be made to have high anti-reflective performance not only for obliquely incident light but also for perpendicularly incident light. The adhesion of particles in the paint can be observed, for example, by washing the paint with water or a solvent, separating the fibers from the paint by filtration or centrifugation, and then observing it using an optical microscope or a transmission electron microscope.

[0047] (Resin) The resin contained in the paint refers to the uncured resin composition. The resin may be dissolved in the paint or may be an uncrosslinked prepolymer. The type of resin is not particularly limited and may be a single resin or a mixture. Examples of usable resins include acrylic resins, polyester resins, alkyd resins, fluororesins, epoxy resins, polyurethane resins, and polyether resins. Copolymers of each resin may also be used, with acrylic urethane resin being preferred. In addition to the resin, a resin composition containing additives and solvents may also be used. Resin compositions can be one-component curing type or two-component curing type, and either may be used. Among these, the two-component curing type is preferred from the viewpoint of adhesion and strength to resin substrates and metal substrates.

[0048] (Solvent) The solvent may be water or may contain an organic solvent, and can be selectively used according to the application of the paint. Paints with water as the main component have the advantage of low environmental impact. When an organic solvent is included, the adhesion and easy drying properties of the paint film are enhanced, and the types of resin components that can be used are different from those in the case of containing water. The organic solvents that can be used may be those commonly used in paints. For example, alcohols (such as methanol, ethanol, isopropanol, n-butyl alcohol, ethylene glycol, etc.), ketones (such as acetone, methyl ethyl ketone, etc.), esters (such as ethyl acetate, butyl acetate, etc.), halides (such as chloroform, methylene chloride, etc.), olefins (such as butane, hexane, etc.), ethers (such as tetrahydrofuran (THF), butyl ether, dioxane, etc.), aromatics (such as benzene, xylene, toluene, etc.), amides (such as N,N-dimethylformamide, dimethylacetamide) can be mentioned. Also, these mixed solvents can be mentioned. The solvent is preferably selected considering the balance between the solubility of the resin and the affinity for the particles, and it is preferable that the resin is well dissolved and the affinity for the particles is not too high. The affinity can be defined by known methods such as surface energy or HSP value or SP value. If the affinity for the particles is too high, there is a risk that the solvent in which the resin is dissolved will easily stay in the recesses of the fiber 31 depending on the manufacturing method. Also, if the affinity for the particles is too low, there is a risk that the particle dispersibility will be poor and the storage stability of the paint will be impaired depending on the manufacturing method. Therefore, in the case of particles suitable for the above-mentioned aqueous treatment, an organic solvent system is more preferable, and in the case of particles suitable for solvent-based treatment, an aqueous solvent is more preferable.

[0049] <Method for manufacturing an antireflection paint> The manufacturing method of the paint of the present disclosure is not particularly limited, but a suitable manufacturing method will be described below.

[0050] First, a fiber having a convex portion at the periphery and a concave portion that is recessed toward the axial center from the convex portion, particles and / or particle precursors, and an aqueous solvent are mixed to obtain a mixed liquid (S01). When the fiber, the particles or the particle precursors, and the aqueous solvent are mixed and dried, the drying gradually progresses from the convex portion of the fiber, and the aqueous solvent accumulates in the concave portion while increasing the concentration of the particles or the particle raw materials.

[0051] Next, the mixture is dried to obtain fibers in which the particles and / or particle precursors are attached to the protrusions and recesses (S02). When the mixture is dried, many particles accumulate in the recesses. Here, it is preferable that the aqueous solvent has a high surface tension, as this makes it easier for particles and particle precursors to accumulate in the recesses. It is not necessary for particles to adhere to the recesses; particle precursors may also be present. Examples of particle precursors include inorganic salts and siloxane compounds. Examples of inorganic salts include sodium chloride, barium chloride, magnesium chloride, aluminum chloride, sodium aluminate, sodium zirconate, sodium hydroxyzincate, magnesium sulfate, sodium silicate, sodium carbonate, and sodium sulfate. Examples of silane compounds include alkyltrimethoxysilane, alkyltriethoxysilane, such as methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, octyltrimethoxysilane, tetraethoxysilane, vinyldimethoxymethylsilane, vinyltriethoxysilane, vinyltriacetoxysilane, isooctyltrimethoxysilane, isooctyltriethoxysilane, N-trimethoxysilylmethyl-O-methylcarbamate, N-dimethoxy(methyl)silylmethyl-O-methylcarbamate, hexadecyltrimethoxysilane, 3-octanoylthio-1-propyltriethoxysilane, and compounds thereof.

[0052] Then, the fibers to which the particles and / or particle precursors are attached, the resin, and the solvent are mixed (S03). The means of mixing are not particularly limited, as long as the short fibers can be dispersed in the paint. Examples include a jet mill, mixer, magnetic stirrer, dissolver, paint shaker, rotator, etc. The paint of this disclosure can be obtained by following the above procedure.

[0053] <Method for Manufacturing Optical Components> The method for manufacturing an optical component, which is an example of a component of this disclosure, is not particularly limited, but preferred manufacturing methods are described below.

[0054] First, the above-mentioned paint and solvent are mixed to obtain a mixed solution (S11). A curing agent may also be included during mixing. In particular, when using a two-component curing type resin, it is preferable to mix the curing agent in addition to the solvent.

[0055] Next, the resulting mixture is spray-coated onto the substrate (S12). Spray coating has the advantage that, as soon as the paint droplets land on the substrate, drying proceeds quickly, which prevents the fibers from collapsing and makes it easier to form a thick fibrous structure.

[0056] Then, the spray-coated substrate is dried (S13). Drying may be done by heating or by drying at room temperature. The component of this disclosure can be obtained by following the above procedure.

[0057] As described above, in the second embodiment, in the fibers having recesses and protrusions contained in the paint, which is the raw material for the film, the particles adhering to the recesses of the fibers are greater than the particles adhering to the protrusions. Therefore, the capillary force acting on the recesses is weakened by the adhesion of particles, and after application to the substrate, the resin component or the resin containing the solvent is more likely to flow out to the protrusions or the resin layer side. Thus, the film obtained by drying the paint of this disclosure has suppressed surface reflection in the fiber structure (fiber layer). As a result, the film obtained by drying the paint of this disclosure has high anti-reflective performance not only for obliquely incident light but also for perpendicularly incident light.

[0058] [Embodiment 3] <Aerosol Can Containing Paint> Figure 4 is a schematic diagram of an aerosol can according to the present disclosure. The aerosol can 60 comprises a liquid container 62 containing the paint of Embodiment 2, a gas container 61 containing a propellant, and a connecting member 63 connecting the liquid container 62 and the gas container 61. The method of use is not limited, but it can be used, for example, as exterior wall paint for buildings, automotive paint, or toy paint.

[0059] The liquid container 62 is a container for storing anti-reflective paint. The liquid container 62 may have, for example, a cylindrical container body, and the inside of the container may be divided into liquid spaces. The paint is filled into the liquid container 62 and connected to the gas container 61.

[0060] The gas container 61 comprises, for example, a metal cylinder filled with a propellant and a holder attached to the cylinder. The propellant stored in the cylinder is not particularly limited, and various known propellants used in aerosol products can be used. For example, liquefied gas, compressed gas, etc. can be used as the propellant. Examples of the liquefied gas include various liquefied petroleum gases, dimethyl ether, and liquefied gases mixed therewith. Examples of the compressed gas include compressed air, nitrogen gas, carbon dioxide, and other compressed gases. For example, the container may have a cylindrical body, and the gas space and liquid space inside the container may be connected. By pressing a button installed on the container body, the propellant and paint may be mixed within the connecting member and ejected to the outside of the container. The above is an example of a spray can for a one-component paint, but when using a two-component curing type paint, a system that makes it difficult for the curing reaction to occur when not in use is more preferable. For example, a design in which the liquid chambers for the paint and the hardener are separated is preferred, and specifically, known spray can designs such as those described in Japanese Patent Publication No. 2018-177244 and Japanese Patent Publication No. 2009-23684 can be used.

[0061] [Embodiment 4] <Device Application> (Optical Instrument, Imaging Device) Figure 5 is a schematic diagram showing one embodiment of the configuration of a single-lens reflex digital camera 600, which is an example of an imaging device, and is equipped with a lens barrel, which is an example of a preferred embodiment of the imaging device of the present disclosure. In Figure 5, the camera body 602 and the lens barrel 601, which is an optical instrument, are coupled together, and the lens barrel 601 is a so-called interchangeable lens that can be attached to and detached from the camera body 602.

[0062] Light from the subject is received by the image sensor and captured when it passes through an optical system consisting of multiple lenses 603, 605, etc., which are an example of components arranged on the optical axis of the imaging optical system inside the housing of the lens barrel 601. Here, lens 605 is supported by an inner barrel 604 and is movably supported relative to the outer barrel of the lens barrel 601 for focusing and zooming. The inner barrel 604 is a support that supports lens 605.

[0063] During the observation period before shooting, light from the subject is reflected by the main mirror 607, which is an example of a component inside the camera body housing 621, passes through the prism 611, and the image is projected onto the photographer through the viewfinder lens 612. The main mirror 607 is, for example, a half-mirror, and the light that passes through the main mirror is reflected by the sub-mirror 608 towards the AF (autofocus) unit 613, and this reflected light is used, for example, for distance measurement. The main mirror 607 is also attached and supported to the main mirror holder 640 by adhesive or the like. During shooting, the main mirror 607 and sub-mirror 608 are moved out of the optical path via a drive mechanism (not shown), the shutter 609 is opened, and the image of the photographic light incident from the lens barrel 601 is projected onto the image sensor 610. The aperture 606 is configured to change the brightness and depth of field during shooting by changing the aperture area.

[0064] To apply the component 100 of this disclosure to a lens barrel, the housing 620 has the same configuration as the base material 1, and an anti-reflective film 630 with the same configuration as the film 10 is provided on the inner wall surface 620A of the housing. Alternatively, the inner cylinder 604 has the same configuration as the base material 1, and an anti-reflective film 630 with the same configuration as the film 10 is provided on the first surface 604A of the support, which is the surface of the inner cylinder that supports the lens. By adopting such a configuration, light rays that do not form an image and do not contribute to the formation of an image of the subject among the light rays incident on the optical instrument are less likely to return to the optical path by hitting the fiber structure. As a result, the amount of stray light reaching the image sensor 610 is reduced. According to the imaging device of this disclosure, since the amount of stray light reaching the image sensor is reduced, it is possible to provide an imaging device that is less prone to flare and ghosting and has excellent image quality.

[0065] Although a single-lens reflex digital camera was used as an example to describe the imaging device, this disclosure is not limited to this and may also include smartphones or compact digital cameras. Furthermore, it may also include automotive modules such as automotive cameras, ADAS (Advanced Driver-Assistance Systems) cameras, and LiDAR (Optical Detection and Distance Measurement) modules, which have lenses or mirrors and image sensors or light-receiving elements.

[0066] (Display Device) Figure 6 is a schematic diagram showing one embodiment of the configuration of a head-up display 300, which is an example of a preferred embodiment of the display device of the present disclosure.

[0067] The head-up display 300 is installed in a vehicle such as an automobile and projects image light onto the windshield 8, which is an example of a display unit, to display a virtual image IM that can be seen by a viewer, such as a driver, who has eyes 9. The head-up display 300 has a housing 13, an image generation unit 4, and reflectors 51 and 52. The head-up display 300 is installed, for example, in the dashboard in front of the steering wheel H.

[0068] The image generation unit 4 is located inside the housing 13. The image generation unit 4 includes a light source 42 and a display panel 41. The light source 42 is a device that emits light, such as a plurality of LEDs. The display panel 41 is a device that modulates the light emitted from the light source 42 to generate image light, such as a self-emissive display like a transmissive liquid crystal display or an organic EL display.

[0069] The reflectors 51 and 52 are installed inside the housing 13. Each reflector 51 and 52 has a reflective surface 51A and 52A, respectively, and reflects the image light generated by the image generation unit 4 at each reflective surface. Before being reflected by the reflective surface 51A, the generated image light may, if necessary, pass through an optical path via a focusing lens 53 or the like. The reflector 52 has a drive mechanism 521 including a motor and gears, and the drive mechanism 521 is driven by a control device (not shown), allowing adjustment of the angle of the reflective surface 52A. Each reflector 51 and 52 is a concave mirror. Each reflector 51 and 52 has a free-form surface made of resin on which a metal film such as aluminum is formed. The metal film can be formed, for example, by vapor deposition. The image light reflected by the reflector 52 is magnified and projected toward the front glass 8 located on the outside of the housing 13 via the transmissive plate 7. The transmissive plate 7 is, for example, an acrylic plate.

[0070] To apply the component 100 of this disclosure to a display device, the housing 13 has the same configuration as the base material 1, and an anti-reflective film 210 having the same configuration as the film 10 is provided on the inner wall surface 13A of the housing. By adopting this configuration, light rays generated when the backlight of the head-up display is turned on or when ambient light is incident, and light rays that do not contribute to the formation of reflected image light within the housing, are less likely to return to the optical path by hitting the fiber structure. As a result, the amount of stray light reaching the display area 81 of the windshield 8 is reduced. With the display device of this disclosure, since the amount of stray light reaching the windshield 8 is reduced, it is possible to provide a display device with excellent image (virtual image) quality generated from image light.

[0071] In the embodiments of the display device described herein, the case in which a head-up display is installed in an automobile was described as an example, but it is also applicable to other vehicles such as trains and airplanes. It is also applicable to uses other than vehicles. Furthermore, it is also applicable to display devices such as projectors used indoors or outdoors. In Figure 6, the anti-reflective coating 210 is provided at three locations on the inner wall surface 13A of the housing 13, but the number and position of the anti-reflective coating provided inside the housing 13 are not limited to this form. Also, although two reflectors are provided inside the housing 13, depending on the design of the optical system, there may be only one reflector.

[0072] (Building Material) Figure 7 is a schematic diagram of a building which is an example of a building material of the present disclosure. The building material is an example of a member comprising a base material and a film provided on the base material. The building 70 includes an exterior wall 73, windows 71 and doors 72. To apply the member 100 of the present disclosure to the building 70, the exterior wall 73 is made to have the same configuration as the base material 1, and the film 10 is provided on it. The film 10 exhibits attractive reflective properties to visible light, making it highly aesthetically pleasing. Furthermore, because it absorbs a lot of light, it can be used as a heat-absorbing material, making it highly valuable as a building material. In addition to the exterior walls of buildings, it can also be suitably used for the exterior of automobiles, etc.

[0073] (Clothing and Blackout Curtains) Figure 8 is a schematic diagram of a poncho, which is an example of clothing according to the present disclosure. Clothing is an example of a member comprising a base material and a membrane provided on the base material. The poncho 500 includes sleeves 501 and a body 502. To apply the member 100 of the present disclosure to the poncho 500, the sleeves 501 and body 502 are made to have the same configuration as the base material 1, and the membrane 10 is provided thereon. The membrane 10 exhibits aesthetically pleasing reflective properties to visible light, making it highly suitable for use in clothing. Furthermore, because it has low reflectivity in the near-infrared region, it can block infrared rays, resulting in clothing that is black but has a heat-shielding effect. On the other hand, due to its properties, it has the advantage of being difficult to see with imaging devices that utilize lasers, such as night vision cameras and LiDAR, making it suitable for use as a blackout curtain to emphasize traffic signs.

[0074] (Camera Mounting Device) Figure 9 is a schematic diagram of an in-vehicle camera bracket, which is an example of a camera mounting device of the present disclosure. The bracket 700 is an example of an optical member comprising a base material and a film provided on the base material. The bracket is for mounting an in-vehicle camera on the windshield of an automobile and includes a bracket body portion 701 having a main body adhesive portion that adheres to the windshield, a camera mounting portion 702 connected to the bracket body portion 701 to which an imaging means, which is the in-vehicle camera, is attached, and a camera front portion 703 which is an embodiment of a camera hood positioned in front of the camera front portion 703. To apply the member 100 of the present disclosure to the bracket 700, it is preferable to have the same configuration as the base material 1 for the camera front portion 703 and to provide the film 10 on it. By adopting such a configuration as an in-vehicle camera module with an in-vehicle camera mounted on the bracket 700, light rays that do not contribute to the formation of the subject image among the light rays incident on the in-vehicle camera are less likely to return to the optical path because they hit the fiber structure. As a result, the amount of stray light reaching the in-vehicle camera, its optical system, and at least one of the image sensor is reduced. Furthermore, by positioning the front of the camera facing the mounting surface, stray light originating from light perpendicularly incident from the mounting surface, such as sunlight, can be prevented. According to the camera mounting device of this disclosure, the amount of stray light reaching the camera, its optical system, and at least one of the image sensor is reduced. Therefore, images with excellent quality that are less prone to flare and ghosting can be obtained, making it suitable for use in ADAS (Advanced Driver-Assistance Systems) and the like. The bracket may also have a heating mechanism to prevent glass fogging and a textured structure to prevent reflection. Although a mounting device for an in-vehicle camera with the mounting location on the windshield has been described as an example, this disclosure is not limited to this, and the mounting location may be, for example, the windshield glass, sunroof glass, or rear glass. Also, there may be one camera or multiple cameras to be mounted.

[0075] <Method for Evaluating Anti-Reflection Function> The anti-reflection function of the film in this embodiment can be evaluated by its reflectance. For example, a component can be prepared by applying a coating film to the surface of a 50 mm x 50 mm substrate made of polycarbonate, and the reflectance at incident angles of 5° and 80° can be measured using an ultraviolet-visible-near-infrared spectrophotometer (manufactured by JASCO Corporation, product name: V-770).

[0076] The present disclosure will be described in more detail below with reference to examples and comparative examples, but the present disclosure is not limited in any way by the following examples unless it exceeds the gist of the disclosure. Unless otherwise specified, amounts of components expressed in "parts" and "%" are based on mass.

[0077] <Preparation of short fibers> (Preparation of short fibers 1-18 and comparative short fibers 1 and 2) First, as shown in Figure 3D, fiber A (manufactured by Teijin Frontier Co., Ltd., product name: Octa) was prepared, having a square cross-section and recesses inscribed in the periphery of the square. Fiber A is made of polyester, has a thickness T of 25 μm, and is a hollow 8-fin fiber with eight protrusions and eight recesses with a width S of 10 μm. The fibers wound on a bobbin were bundled into a tow shape using a skein lifting machine and immersed in water. The tow-shaped fibers were removed from the water and the moisture content was measured to be 50% of the total weight. Next, the tow-shaped fibers were fed on a belt conveyor and continuously cut with a guillotine cutter to produce 60 kg of pile with a length of 200 μm. The obtained pile was washed, pressure dyed with a black disperse dye, dried, and recovered.

[0078] Next, the mixture was added to 300 L of water heated to 60°C, and 0.9 kg of colloidal silica with a particle size of 0.03 μm (manufactured by Nissan Chemical Corporation, trade name Snowtex ST-O) and 2.1 kg of alumina sol with a particle size of 0.01 μm (manufactured by Nissan Chemical Corporation, trade name AS-520-A) were added and stirred for 30 minutes. The resulting aqueous dispersion was filtered and dehydrated. Then, it was dried at 80°C using a dryer to obtain short fibers 1.

[0079] Observation of the obtained short fiber 1 using a transmission electron microscope (Hitachi High-Tech, product name SU-70) revealed that it was covered with a first particle with an average particle diameter of approximately 0.01 μm and a second particle with an average particle diameter of approximately 0.03 μm. The image showed that 80% of the area of ​​the recesses was covered with the first and second particles, and 20% of the area of ​​the convex parts was covered with the first and second particles. Elemental analysis of the first and second particles revealed that the first particle was mainly composed of Al, and the second particle was mainly composed of Si. Based on these results and the components added, it is assumed that they were alumina sol and colloidal silica, respectively.

[0080] Table 1 summarizes the conditions and characteristics of short fiber 1. Short fibers 2 to 18 were obtained using the same process as short fiber 1, except for the fiber, length, reagents added after staining, and concentration shown in the left side of Table 1. The coverage rates of the concave and convex parts of each fiber are shown in the right side of Table 1. Note that for fiber G, since it is a fiber dope-dyed with carbon black, pressure staining was not performed. The reagent added after staining short fiber 9 was porous silica (manufactured by Fuji Silysia Chemical Co., Ltd., trade name Silysia 358). Comparative short fiber 1 was obtained using the same process as short fiber 1, except that fiber H was used. Due to the lack of a surface texture, the particle coverage rate was low, at 4%. Comparative short fiber 2 was obtained using the same process as short fiber 1, except that colloidal silica and alumina sol were not added to fiber C.

[0081] Furthermore, the fibers A to H used are as follows: (Fiber A) Hollow 8-fin fiber (manufactured by Teijin Frontier Co., Ltd.) Cross-sectional shape: Figure 3E, Material: Polyester, Thickness T: 25 μm, Width S: 10 μm, Number of recesses: 8, Dyed with black dye (Fiber B) Hollow 8-fin fiber (manufactured by Teijin Frontier Co., Ltd.) Cross-sectional shape: Figure 3E, Material: Polyester, Thickness T: 50 μm, Width S: 20 μm, Number of recesses: 8, Dyed with black dye (Fiber C) Y-shaped fiber (manufactured by Toray Industries, Inc.) Cross-sectional shape: Figure 3F, Material: Rayon, Dyed with black dye (Fiber D) Crimped fiber (manufactured by Teijin Frontier Co., Ltd.) Cross-sectional shape: Figure 3G, Material: Polyester, Thickness T: 9 μm, Width S: 2 μm, Number of recesses: 4, Dyed with black dye (Fiber E) Alkali-reduced fiber (manufactured by Teijin Frontier Co., Ltd.) Cross-sectional shape: Figure 3C, Material: Polyester, Thickness T: 80 μm, Width S: 22 μm, Number of recesses: Average 11, Dyed with black dye (Fiber F) Petal-shaped nylon fiber (manufactured by Kuraray Co., Ltd.) Cross-sectional shape: Figure 3H, Material: Nylon, Thickness T: 15 μm, Width S: 5 μm, Number of recesses: 5, Dyed with black dye (Fiber G) Hollow 8-fin dope-dyed fiber (manufactured by Teijin Frontier Co., Ltd.) Cross-sectional shape: Figure 3E, Material: Polyester, Thickness T: 25 μm, Width S: 10 μm, Number of recesses: 8, Dyed with black dye (Fiber H) Spherical nylon fiber (manufactured by Teijin Frontier Co., Ltd.) Cross-sectional shape: Perfectly round, Material: Nylon, Thickness T: 10 μm, Number of recesses: None, Dyed with black dye

[0082] <Preparation of Paint> (Example 1) First, the obtained short fibers 1 were mixed with a two-component acrylic urethane black paint (manufactured by Musashi Paint Holdings Co., Ltd., product name: Neo Lavasan N7812-00) so that the weight of the short fibers was 32% of the total solids weight, and the mixture was stirred for 2 hours using a paint shaker to obtain anti-reflective paint 1.

[0083] (Examples 2-18, Comparative Examples 1 and 2) Anti-reflective coatings 2-18 and comparative anti-reflective coatings 1 and 2 were obtained in the same manner as in Example 1, except that the short fibers and weight concentration were changed to the values ​​shown in Table 2.

[0084] (Example 19) An anti-reflective coating 19 was obtained in the same manner as in Example 1, except that the black paint used to mix the short fibers was changed to an acrylic water-based paint (manufactured by Nichia Paint Co., Ltd., product name: Aqua Black III).

[0085] (Example 20) An anti-reflective coating 20 was obtained in the same manner as in Example 1, except that the black coating used to mix the short fibers was changed to an alkyd coating (manufactured by Natco, product name: Futacoat Black).

[0086] <Preparation of anti-reflective coating and film for spraying> (Example 21) Anti-reflective coating 1, isocyanate curing agent (manufactured by Musashi Paint Holdings Co., Ltd., product name: curing agent H-760), and methyl ethyl ketone (manufactured by Kishida Chemical Co., Ltd.) as thinner were mixed in a ratio of anti-reflective coating:curing agent:thinner of 100:10:40, and stirred with a spatula for 3 minutes to obtain anti-reflective coating 1 for spraying. The obtained anti-reflective coating 1 for spraying was applied to a substrate at a pressure of 0.4 MPa using a spray gun with a nozzle diameter of 1.8 mm (manufactured by Anest Iwata, product name: WIDER-2-18K2G), and heated and dried in an oven at 120°C for 2 hours to obtain coating film 1. A black polycarbonate sheet (manufactured by Mitsubishi Gas Chemical Co., Ltd., product name: Yupiron) was used as the substrate.

[0087] (Examples 22-38, Comparative Examples 3, Comparative Example 4) Spray anti-reflective coatings 2-18 and comparative spray anti-reflective coatings 1,2 were obtained in the same manner as in Example 21, except that the anti-reflective coating used was changed to those listed in Table 3. Coating films 2-18 and comparative coating films 1,2 were obtained by coating and drying in the same manner as in Example 21. In Table 3, MEK is methyl ethyl ketone and PC is polycarbonate.

[0088] (Examples 39-42) Spray paints 19-22 were obtained in the same manner as in Example 21, except that the anti-reflective paint used and the ratio of anti-reflective paint:hardener:thinner were changed to those listed in Table 3. The paint films 19-22 were then applied and dried in the same manner as in Example 21.

[0089] (Examples 43-46) Coating films 23-26 were obtained in the same manner as in Example 21, except that the base materials used were aluminum die-cast ADC12 (manufactured by Standard Test Piece Co., Ltd.), SUS plate SUS301 (manufactured by Test Piece Co., Ltd.), butadiene-acrylonitrile rubber (manufactured by Naigai Rubber Co., Ltd., product name: Hanenite GP60LE), and polyester nonwoven fabric (manufactured by Shimojima Co., Ltd., product name: Flower Wrap). It was confirmed that the fiber structure of coating films 25 and 26 followed the curve even when bent 180°.

[0090] <Evaluation of Coating Film> (Evaluation of Film Thickness) The cross-sections of the coating films for the examples and comparison were broken, and the thickness of the resin layer and fiber layer was measured by observation using a transmission electron microscope (Hitachi High-Tech Science, product name: SU-70). The measurement results and the total thickness are shown in Table 4.

[0091] (Evaluation of Resin Content) The fiber layer was scraped off using a cutter and held at 340°C in air for 1 hour using a thermogravimetric differential thermal analyzer (Hitachi High-Tech Science, product name: TG / DTA STA7200). The combustion and thermal decomposition temperature of the short fibers was around 360°C, and the combustion and thermal decomposition temperature of the acrylic urethane resin was around 200°C, so the mass reduction of the resin component could be measured. The weight reduction of the scraped fiber layer was divided by the total weight of the original fiber layer and multiplied by 100 to obtain the value representing the resin component content in the fiber layer. The measurement results are shown in Table 4.

[0092] (Evaluation of Reflectance) The reflectance of the coating film at incident angles of 5° and 80° was measured using the absolute reflectance measurement unit (ARMN-920) of a UV-Vis-Near-Infrared Spectrophotometer (manufactured by JASCO Corporation, product name: V-770) at incident angles of 5° and 80°. The wavelength of the incident light was measured every 2 nm in the range of 550 nm to 650 nm, and baseline correction was performed. The measurement results and evaluation ranks, with the average value of the obtained data used as the reflectance at 600 nm, are shown in Table 3. The evaluation ranks were set as follows: 5° Incidence: A: Reflectance less than 0.05, showing good anti-reflective performance. B: Reflectance 0.05 or more and less than 0.15, within the acceptable range for an anti-reflective coating. C: Reflectance 0.15 or more, within the unacceptable range for an anti-reflective coating. 80° Incidence: A: Reflectance less than 0.30, showing good anti-reflective performance. B: The reflectivity was between 0.3 and 1, which was within the acceptable range for an anti-reflective coating. C: The reflectivity was 1 or higher, which was outside the acceptable range for an anti-reflective coating.

[0093] Furthermore, when the reflectance of coating film 1 was measured using the same method except that the wavelength of the incident light was set to 1450 nm to 1550 nm, it showed very low reflectances of 0.03% for 5° incident light and 0.49% for 80° incident light.

[0094] (Evaluation of Adhesion) The adhesion of the coating film was evaluated using a tape cross-cut test in accordance with JIS-K5600-6. The evaluation rank was set as follows, according to the evaluation result classification of the JIS standard. The evaluation results are shown in Table 4. A: Classification 0... No peeling at all, showing good adhesion. B: Classification 1-3... Somewhat prone to peeling, but within a range acceptable for practical use. C: Classification 4-5... Prone to peeling, and within an unacceptable range for a coating film.

[0095] <Preparation of spray can> (Example 47) A spray paint 10 was filled into a refillable sprayer (manufactured by FIRSTINFO), and air was added at a pressure of 0.4 MPa to produce a spray can as Example 47. It was confirmed that spray painting was possible by pressing the button on the top of the container and that there were no blockages.

[0096] <Manufacturing of optical instruments, imaging devices, display devices, buildings, and clothing> (Example 48) A square tube was made by bonding coating films 1 together, and one end of the tube was sealed with an illuminometer to create an optical measuring instrument as a simple Example 48 with an optical path. When 100 lx of light was shone through the hole in the optical instrument, it showed an illuminance of 100 lx, confirming that stray light was suppressed.

[0097] (Example 49) An imaging device (manufactured by lomography, product name: Konstruktor F camera) was fabricated as Example 49 by applying a coating to the inner wall surface of the lens barrel in the same manner as in Example 21. When a subject placed 1m in front of a high-intensity lightbox (manufactured by TRIOPTICS, product name LG3) with an illuminance set to 150,000 lx was photographed from a distance of 3m, it was confirmed that flare and ghosting were suppressed.

[0098] (Example 50) A projection device was fabricated in the same manner as in Example 48, except that an illuminance meter was used as the projector, and a display device was fabricated as Example 50, which projects an image onto a glass screen. It was confirmed that the display device had minimal reflection on the glass.

[0099] (Example 51) The coating film 1 was applied to the exterior wall of a building to produce a building material as Example 51. It was confirmed that the exterior wall was matte and aesthetically pleasing.

[0100] (Example 52) The coating 26 of the polyester nonwoven fabric base material prepared in Example 46 was cut to conform to the wearer, and the two pieces of fabric, the front and back, were sewn together to create a poncho, which is an example of clothing that covers the wearer's body, as Example 51. It was confirmed that the garment was non-glossy and aesthetically pleasing.

[0101] (Example 53) The bracket shown in Figure 9 was molded using PBT resin, and a cut piece of coating 26 was attached to the front part 703 of the camera. Double-sided tape for glass (manufactured by 3M Corporation, product name: Scotch Tape for Glass) was attached to the upper surface of the bracket body to create a simple camera mounting device as Example 53. An imaging device (manufactured by lomography, product name: Konstruktor F camera) was attached to the camera mounting part, and the device was attached to the windshield of a car to check its function as an in-vehicle camera. It was confirmed that flare and ghosting were suppressed.

[0102]

[0103]

[0104]

[0105]

[0106] As shown in Table 4, all coatings 1 to 26 received good reflectance evaluations of A or B. In contrast, both comparative coatings 1 and 2 received reflectance evaluations of C.

[0107] Furthermore, the short fibers in Example 12 were 800 μm long, which was longer than the short fibers in the other examples, so it took time to determine the optimal spray coating conditions. Therefore, it was confirmed from the experiment that it is preferable for the length of the short fibers to be 400 μm or less.

[0108] <Preparation of short fibers 2> Using the same method as in the preparation of short fibers 1, fiber A was cut to a length of 500 μm, and 15 kg of the resulting pile was placed in 300 L of water heated to 60°C. 1.2 kg of alum and 0.018 cm³ of formic acid (purity 77% by mass) were added, and the mixture was stirred for 10 minutes. Next, 0.3 kg of tannic acid was added, and the mixture was stirred for 20 minutes. Subsequently, another 0.3 kg of alum was added, and the mixture was stirred for 10 minutes. After that, the mixture was filtered without washing and dehydrated. The resulting pile was placed in 150 L of water containing 0.1 kg of surfactant and 0.1 kg of zirconium carbonate, and stirred at 45°C for 10 minutes. The resulting aqueous dispersion was filtered and dehydrated. The mixture was then dried in a dryer at 80°C to obtain short fibers 19.

[0109] When the obtained short fibers 19 were observed using a transmission electron microscope (Hitachi High-Tech, product name SU-70), it was found that particles with an average particle diameter of approximately 0.01 μm were attached and densely packed within them. Images were obtained showing that 70% of the area of ​​the recesses was covered by the first particles, and 35% of the area of ​​the convex parts was covered. Elemental analysis of the particles revealed that they were mainly composed of zirconium.

[0110] Next, using the fibers shown in the left side of Table 5, short fibers 20 to 32 were obtained in the same manner as the process for obtaining short fiber 19, except for the fiber length and the zirconium carbonate concentration added after dyeing. The coverage rates of the recesses and protrusions for each are shown in the right side of Table 5. The manufacturing conditions and characteristics of short fibers 19 to 32 are summarized in Table 5.

[0111] (Examples 54-67) Anti-reflective coatings 21-34 were prepared in the same manner as in Example 1, except that short fibers 19-32 were used, so that the short fiber concentration was 32%. The correspondence between the short fibers used and the prepared coatings is summarized in Table 5.

[0112]

[0113] (Examples 68-81) Spray anti-reflective coatings 23-36 were obtained in the same manner as in Example 21, except that anti-reflective coatings 21-34 were used. The obtained spray anti-reflective coatings were applied to a substrate at a standard pressure of 0.2 MPa using spray guns with different pore sizes (manufactured by Anest Iwata), heated and dried in an oven at 120°C for 2 hours, and the discharge performance was evaluated. In addition, the film thickness, resin content, reflectivity, and adhesion of the coating films 27-40, which were created during the first discharge test, were evaluated. The evaluation results are shown in Table 6. A black polycarbonate sheet (manufactured by Mitsubishi Gas Chemical, product name: Yupiron) was used as the substrate.

[0114]

[0115] (Evaluation of discharge performance) Ten A4-sized black polycarbonate sheets (manufactured by Mitsubishi Gas Chemical, product name: Yupiron) were painted using spray guns of each nozzle size, and the presence or absence of clogging after painting all ten sheets was checked. The experiment was conducted three times, and the evaluation ranks were set as follows: A: Clogging occurred 0 times out of 3. Shows good discharge stability under standard conditions. B: Clogging occurred 1 time out of 3. Conditions need to be refined. C: Clogging occurred 2 times out of 3. Conditions need to be refined. D: Clogging occurred 3 times out of 3. Stable discharge is difficult.

[0116] Table 7 shows the results of the discharge performance evaluation of the prepared spray paints 23 to 36.

[0117]

[0118] The results showed that the shorter the short fiber length, the higher the discharge stability. It was also found that if the fiber length is 400 μm or less, it is highly likely that it can be used in spray guns with a 1.0 mm pore size, which are readily available commercially.

[0119] The present invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, the following claims are attached to make the scope of the invention public.

[0120] This application claims priority based on Japanese Patent Application No. 2024-228805, filed on 25 December 2024, and Japanese Patent Application No. 2025-024002, filed on 18 February 2025, and all of the contents of those applications are incorporated herein by reference.

Claims

1. A paint comprising fibers, particles, a resin, and a solvent, wherein the fibers have convex portions on their periphery and concave portions that are recessed toward the axial center from the convex portions, the particles are attached to the fibers, and the amount of particles attached to the concave portions is greater than the amount of particles attached to the convex portions.

2. The paint according to claim 1, wherein the fiber content is in the range of 5 parts by mass or more and less than 33 parts by mass per 100 parts by mass of paint solids.

3. The paint according to claim 1 or 2, wherein the particle diameter of the particles is smaller than the width of the recess.

4. The paint according to claim 3, wherein the width of the recess is in the range of 0.5 μm or more and 30 μm or less.

5. The paint according to any one of claims 1 to 4, wherein the particles include first particles, and the first particles are inorganic particles.

6. The paint according to claim 5, wherein the inorganic particles contain 10 atomic percent or more of aluminum.

7. The paint according to any one of claims 1 to 6, wherein the particles include a second particle, and the second particle is made of a porous material.

8. The paint according to claim 7, wherein the second particle contains 10 atomic percent or more of silicon.

9. The paint according to any one of claims 1 to 8, wherein the fiber is made of polyester.

10. The paint according to any one of claims 1 to 9, wherein the length of the fiber is in the range of 1 μm or more and 1000 μm or less.

11. The paint according to claim 10, wherein the length of the fiber is 400 μm or less.

12. The paint according to any one of claims 1 to 11, wherein the aspect ratio of the fibers is in the range of 5 to 500.

13. The paint according to any one of claims 1 to 12, wherein the fiber is a hollow fiber.

14. The paint according to any one of claims 1 to 13, wherein the fiber is a black dope-dyed yarn.

15. A spray can comprising a liquid container storing the paint described in any one of claims 1 to 14, a gas container storing a propellant, and a connecting member connecting the liquid container and the gas container.

16. A film comprising a resin layer made of resin, fibers protruding from the resin layer, and particles, wherein the fibers have convex portions at their periphery and concave portions that are recessed toward the axial center from the convex portions, the particles are attached to the fibers, and the amount of particles attached to the concave portions is greater than the amount of particles attached to the convex portions.

17. The film according to claim 16, wherein the length of the fibers protruding from the resin layer is in the range of 30 μm or more and 300 μm or less.

18. The film according to claim 16 or 17, wherein at least a portion of the fibers is covered with the resin constituting the resin layer.

19. The film according to claim 18, wherein the content of the resin covering the fibers protruding from the resin layer is 30 parts by mass or less with respect to 100 parts by mass of the protruding fibers and the resin covering the fibers.

20. The film according to any one of claims 16 to 19, wherein the fiber content is in the range of 5 parts by mass or more and less than 33 parts by mass per 100 parts by mass of the film.

21. The film according to any one of claims 16 to 20, wherein the particle diameter of the particles is smaller than the width of the recess.

22. The film according to any one of claims 16 to 21, wherein the width of the recess is in the range of 0.5 μm or more and 30 μm or less.

23. The film according to any one of claims 16 to 22, wherein the particles include a first particle, and the first particle is an inorganic particle.

24. The film according to claim 23, wherein the inorganic particles contain 10 atomic percent or more of aluminum.

25. The film according to any one of claims 16 to 24, wherein the particles include a second particle, and the second particle is made of a porous material.

26. The paint according to claim 25, wherein the second particle contains 10 atomic percent or more of silicon.

27. The membrane according to any one of claims 16 to 26, wherein the fiber is made of polyester.

28. The film according to any one of claims 16 to 27, wherein the length of the fibers is in the range of 1 μm or more and 1000 μm or less.

29. The membrane according to claim 28, wherein the length of the fiber is 400 μm or less.

30. The membrane according to any one of claims 16 to 29, wherein the aspect ratio of the fibers is in the range of 5 to 500.

31. The membrane according to any one of claims 16 to 30, wherein the fiber is a hollow fiber.

32. The membrane according to any one of claims 16 to 31, wherein the fiber is a black dope-dyed yarn.

33. A member comprising a base material and a film provided on the base material, wherein the film is the film described in any one of claims 16 to 32.

34. An optical member comprising the film described in any one of claims 16 to 32.

35. An optical instrument comprising a housing and an optical system consisting of a plurality of lenses or mirrors within the housing, wherein a film according to any one of claims 16 to 32 is formed on a support that supports the plurality of lenses or mirrors and / or on the inner wall surface of the housing.

36. An imaging device comprising, in addition to the optical instrument described in claim 35, an image sensor that receives light that has passed through the optical system.

37. A display device having an image generation unit that generates image light within the housing of an optical device according to claim 35.

38. A camera mounting device comprising: a bracket for supporting a camera unit having a light-receiving section and for mounting to a surface to be mounted; and a hood having a surface that widens in a direction away from the light-receiving section in front of the camera unit, and which is attached to the bracket such that the surface faces the mounting surface, wherein the surface is formed according to any one of claims 16 to 32.

39. A method for manufacturing a paint, comprising the steps of: mixing a fiber having a convex portion on its periphery and a concave portion that is recessed toward the axial center from the convex portion, particles and / or particle precursors, and an aqueous solvent to obtain a mixed solution; drying the mixed solution to obtain a fiber on which the particles and / or particle precursors are attached to the convex portion and the concave portion; and mixing the fiber to which the particles and / or particle precursors are attached, a resin, and a solvent.

40. A method for manufacturing a component, comprising the steps of: mixing a paint according to any one of claims 1 to 14 with a solvent to obtain a mixed liquid; spray coating the mixed liquid onto a substrate; and drying the spray-coated substrate.

41. The method for manufacturing a member according to claim 40, wherein a curing agent is further mixed in the step of obtaining the mixed liquid.

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