Anti-reflection film, optical member, optical device, imaging device, anti-reflection coating material, and method for producing anti-reflection film

Abstract

To provide an optical member equipped with an antireflection film, which offers both a reduced reflectance and high strength.SOLUTION: An optical member 10 is provided, comprising an antireflection film 12 formed on a base material 11, where the antireflection film 12 comprises a resin layer 4 and deformed fibers 1 bound in the resin layer 4, each fiber having a core portion and a plurality of projections 3 extending from the core portion. Tips of the plurality of projections 3 of the deformed fibers 1 protrude from a surface of the resin layer 4.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a paint having an anti-reflection function, and an optical member, an optical device, and an imaging device provided with an anti-reflection film formed from the paint. [Background technology]

[0002] An optical device such as a lens barrel has an optical system consisting of a housing and multiple lenses installed within the housing. Light rays incident on an optical device are mainly incident on the lens, and the light rays are focused to form a subject image. On the other hand, there are also light rays that are not focused and do not contribute to the formation of the subject image. Light rays that do not contribute to the formation of the subject image are incident from random directions, so they are also incident on things other than optical components such as lenses, and become a cause of unnecessary reflected light and scattered light within the housing. This light is called stray light. If stray light reaches an imaging element, flare and ghosting will occur.

[0003] Various proposals have been made to suppress stray light generated inside an optical device (component) and prevent the occurrence of flare and ghosting. For example, Patent Document 1 discloses that the inner wall surface of an optical component is coated with a black resin containing a plurality of fine particles having a polygonal or elliptical cross section, and the surfaces of the fine particles are made to protrude from the black coating film. Patent Document 2 discloses that the inner wall surface of an optical component is coated with a black resin containing a plurality of spherical fine particles, and the surfaces of the fine particles are made to protrude from the black coating film. These optical components are intended to absorb light rays and reduce reflectance by selecting the material of the fine particles so that the refractive index of the resin matches the refractive index of the protruding fine particles. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2011-64737 A [Patent Document 2] JP 2012-2895 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the optical component disclosed in Patent Document 1 has an inner wall surface with a gloss level of 0.3 at an incidence angle of 60°, and as the incidence angle increases, the effect of reducing the reflectance is insufficient.

[0006] Furthermore, the optical component disclosed in Patent Document 2 has a glossiness of 0.1 at an incidence angle of 85° on the inner wall surface, and the reflectance is reduced. However, since the fine particles are spherical, the contact area with the resin is small, and there is a risk that the fine particles may easily come off inside the optical component (lens barrel).

[0007] Therefore, in an optical member provided with an anti-reflection film, it has been difficult to simultaneously reduce the reflectance and prevent the fine particles from peeling off. [Means for solving the problem]

[0008] The first aspect of the present invention is to provide a method for manufacturing a semiconductor device having a surface. Black A resin layer; Black monster and a fiber, Deformity The fibers are A core and three or more extending from the core Convex part of Have death, The convex portion is arranged on the periphery in a cross section perpendicular to the longitudinal direction of the irregular fiber, The protrusion Tip protrudes from the surface of the resin layer, the length of the protrusion is 2.5 μm or more and 20 μm or less, Deformity The antireflection film is characterized in that the content of the fibers is 33 parts by mass or more and 67 parts by mass or less per 100 parts by mass of the antireflection film. The second aspect of the present invention is a method for producing a surface-based ion exchange membrane comprising: Black A resin layer; Black monster and a fiber, Deformity The fibers are A core and three or more extending from the core Convex part of Have death, The convex portion is arranged on the periphery in a cross section perpendicular to the longitudinal direction of the irregular fiber, The protrusion Tip protrudes from the surface of the resin layer, the length of the protrusion is 2.5 μm or more and 20 μm or less, DeformityThe fiber content is from the anti-reflection film to the Deformity The anti-reflection film is characterized in that the content is 50 parts by mass or more and 200 parts by mass or less per 100 parts by mass excluding fibers. The third aspect for solving the above problem is: Black monster Fibers and Black An anti-reflective coating material containing a resin and an organic solvent, Deformity The fibers are A core and three or more extending from the core Convex Department Has The convex portion is arranged on the periphery in a cross section perpendicular to the longitudinal direction of the irregular fiber, The length of the protrusion is 2.5 μm or more and 20 μm or less, Deformity The anti-reflective coating material is characterized in that the fiber content is 33 parts by mass or more and 67 parts by mass or less per 100 parts by mass of the paint solids. A fourth aspect for solving the above problem is: Black monster Fibers and Black An anti-reflective coating material containing a resin and an organic solvent, Deformity The fibers are A core and three or more extending from the core Convex part of Have death, The convex portion is arranged on the periphery in a cross section perpendicular to the longitudinal direction of the irregular fiber, The length of the protrusion is 2.5 μm or more and 20 μm or less, Deformity The fiber content is Deformity The anti-reflective coating material is characterized in that the content is 50 parts by mass or more and 200 parts by mass or less per 100 parts by mass of the coating solids excluding fibers. Effect of the Invention

[0009] The optical member of the present invention contains irregular fibers having a core and a plurality of convex portions extending from the core, and the tips of the convex portions protrude from the surface of the resin layer, so that light incident between the convex portions can be diffused between the convex portions and prevented from reaching the imaging element. In addition, the binding strength between the irregular fibers and the resin is sufficient. Therefore, it is possible to provide an optical member having a low reflectance of less than 0.2% at an incident angle of 85° and in which the irregular fibers are not easily peeled off. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic diagram showing one embodiment of a non-circular fiber contained in the anti-reflective coating material of the present invention. [Diagram 2] 1 is a schematic diagram showing one embodiment of a non-circular fiber contained in the anti-reflective coating material of the present invention. [Diagram 3] 1 is a schematic diagram illustrating an embodiment of an optical member of the present invention. [Figure 4] 1 is a schematic diagram illustrating an embodiment of an imaging device of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Preferred embodiments of the present invention will now be described.

[0012] <Anti-reflective paint> The anti-reflection coating material used for forming an anti-reflection film on the optical member of the present invention contains a non-circular fiber having a core and a plurality of convex portions extending from the core, a resin, and an organic solvent.

[0013] (irregular fiber) Figures 1 and 2 show an embodiment of a non-circular fiber contained in the anti-reflective coating of the present invention, where Figure 1(a) is a side view in the longitudinal direction, and Figures 1(b) and (c) are cross-sectional views perpendicular to the longitudinal direction. A non-circular fiber refers to a fiber whose cross-sectional shape perpendicular to the longitudinal direction is other than a circle, an ellipse, or a convex polygon with all interior angles smaller than 180°. The non-circular fiber 1 has a core 2 and multiple convex parts 3 extending from the core.

[0014] The length L of the irregular fiber 1 is preferably 0.2 mm or more and 1.0 mm or less. The length of the irregular fiber can be cut to a desired length by a cutter. If the length L of the irregular fiber is shorter than 0.2 mm, the proportion of cut surfaces that do not have anti-reflection function in the irregular fiber increases, and the anti-reflection function may be insufficient. On the other hand, if the length L of the irregular fiber is longer than 1.0 mm, it may be difficult to make the convex part of the irregular fiber protrude from the surface of the resin when an anti-reflection film is formed. In addition, when applying paint with a spray gun, the tip of the spray nozzle may be easily clogged.

[0015] The thickness T of the irregular fiber 1 is preferably 10 μm or more and 50 μm or less. Here, the thickness T of the irregular fiber is the length of the cross section perpendicular to the longitudinal direction of the irregular fiber, in other words, the length of the cross section perpendicular to the fiber axis. The thickness T is the maximum value of the sum of the lengths of the core 2 and the protrusions 3 in the cross section direction. Therefore, in FIG. 1(b), the length indicated by the arrow is the thickness T of the irregular fiber.

[0016] Here, the aspect ratio, which is the ratio (L / T) of the length L to the thickness T of the irregular fiber 1, is preferably 4 or more and 100 or less. When the aspect ratio is in this range, the tips of the convex parts 3 of the irregular fiber are easily protruded from the surface of the resin layer when an anti-reflection film is formed. However, when the aspect ratio is smaller than 4 and approaches an isotropic shape, the cut surface of the irregular fiber is more likely to protrude from the surface of the resin layer, and the anti-reflection function may be insufficient. On the other hand, when the aspect ratio is larger than 100, it becomes difficult to control the orientation of the irregular fiber 1, and the tips of the convex parts 3 may be less likely to protrude from the surface of the resin layer.

[0017] The core 2 is the part drawn by a dotted line in Fig. 1(b) and is circular. However, the core 2 does not necessarily have to be circular, and may be angular. The length of the core (the length of the cross section perpendicular to the longitudinal direction of the irregular fiber) refers to the diameter of the circle when the core is circular, the diameter of the inscribed circle of the polygon when the core is polygonal, and the diameter of the major axis when the core is elliptical. The core 2 may have holes 21 as shown in Fig. 1(c).

[0018] The protrusions 3 extend from the core 2 and are made of the same material as the core 2. Here, although the number of protrusions 3 is eight in FIG. 1(b), there may be two or more protrusions. If there are two or more protrusions, the light incident between the two protrusions can be diffused and prevented from returning to the optical path and reaching the imaging element. In order to diffuse light more efficiently in the irregular fiber, it is preferable that the number of protrusions is three or more and eight or less. Therefore, the effect of the present invention is also achieved with a Y-shape having three protrusions as shown in FIG. 2(a). As an irregular fiber having eight protrusions, for example, Octa (registered trademark) manufactured by Teijin Frontier Co., Ltd. is commercially available. It is difficult to manufacture a fiber having nine or more protrusions.

[0019] Length of protrusion 3 C L The length C of the protrusion 3 is preferably 5 μm or more and 20 μm or less. More preferably, it is 5 μm or more and 12.5 μm or less. L If the length C of the protrusions 3 is smaller than 5 μm, the length of the protrusions 3 protruding from the surface of the resin layer becomes short, and the reflection of light between the protrusions is insufficient, and the effect of reducing the reflectance may be insufficient. L If the distance is greater than 20 μm, the convex portions may tilt or fall, preventing sufficient light from penetrating between the convex portions, and as a result, the effect of reducing the reflectance may be insufficient.

[0020] Thickness C of protrusion 3 T The thickness C of the protrusion 3 is preferably 2 μm or more and 6 μm or less. T If the thickness C of the protrusions 3 is smaller than 2 μm, the protrusions may tilt or fall, and light may not be able to sufficiently penetrate between the protrusions, resulting in an insufficient effect of reducing the reflectance. T If the thickness is greater than 6 μm, the intervals between the multiple protrusions will be small, and light will not be sufficiently reflected between the multiple protrusions, which may result in an insufficient effect of reducing the reflectance.

[0021] Furthermore, the shape of the protrusion 3 does not need to have a rounded tip as in FIG. 1(b), and may have a pointed tip as in FIG. 2(b).

[0022] Furthermore, the protrusions 3 do not need to be formed radially from the core 2 at approximately equal intervals as in FIG. 1(b), and may be of a shape in which the protrusions are not spaced at regular intervals as in FIG. 2(c).

[0023] Moreover, the protrusions 3 do not need to be formed to have a uniform size as in FIG. 1(b), but may have shapes with different sizes as in FIG. 2(d).

[0024] In addition, the cross sections of the irregular fiber 1 in the direction perpendicular to the length direction do not all need to be the same, and an irregular fiber having a shape as shown in Fig. 2(d) may have a shape as shown in Fig. 2(e) in another cross section. An example of a fiber having such a shape is a crimped fiber in which each fiber is shrunk and wound. An example of a commercially available crimped fiber is Calcuro (registered trademark) manufactured by Teijin Frontier Co., Ltd.

[0025] The material of the irregular fiber is not particularly limited, and can be selected from, for example, polyester, nylon, acrylic, polypropylene, rayon, polyethylene, polyurethane, cotton, hemp, knitted wool, and combinations thereof. In order to improve the performance of the anti-reflection film, the irregular fiber may be processed, light-resistant, softened, or fade-resistant.

[0026] The content of the irregular fibers contained in the anti-reflective coating of the present invention is preferably 50 parts by mass or more and 200 parts by mass or less with respect to 100 parts by mass of the paint solid content before mixing the irregular fibers. Here, the paint solid content refers to all solid components contained in the anti-reflective coating, including not only the resin constituting the resin layer described later, but also additives and the like. If the content of the irregular fibers is less than 50 parts by mass, there is a risk that the anti-reflective function will not be sufficiently obtained. On the other hand, if it is more than 200 parts by mass, there is a risk that the tip of the spray nozzle will be easily clogged when applying the paint with a spray gun. In addition, even if an anti-reflective film can be formed, the amount of paint solid content such as resin is small, so that the bonding between the resin layer and the irregular fibers will be insufficient, and the irregular fibers may easily fall off.

[0027] In addition, the content of the irregular fibers, if the irregular fibers are considered to be part of the solid content, can be expressed in other words as 33 parts by mass or more and 67 parts by mass or less per 100 parts by mass of the paint solid content.

[0028] (resin) The resin contained in the anti-reflective coating of the present invention forms a resin layer after the anti-reflective coating is dried. The type of resin is not particularly limited, and can be selected from, for example, acrylic resin, urethane resin, epoxy resin, and combinations thereof. In addition, either a solvent-soluble resin or a reaction-curing resin may be used.

[0029] The resin content of the antireflective coating of the present invention is preferably 5 parts by mass or more and 50 parts by mass or less per 100 parts by mass of the antireflective coating. If the resin content is less than 5 parts by mass, the adhesion to the substrate may deteriorate. On the other hand, if the resin content exceeds 50 parts by mass, it may be difficult to form the antireflective coating into a thin layer.

[0030] (Organic solvent) The type of organic solvent contained in the anti-reflective coating material of the present invention is not particularly limited, and examples thereof include water, thinner, ethanol, isopropyl alcohol, n-butyl alcohol, ethyl acetate, propyl acetate, isobutyl acetate, and butyl acetate. In addition, examples thereof include methyl ethyl ketone, methyl isobutyl ketone, propylene glycol monomethyl ether, toluene, xylene, acetone, cellosolves, glycol ethers, and ethers. These solvents may be used alone or in combination.

[0031] The organic solvent contained in the antireflective coating of the present invention is preferably 5 parts by mass or more and 80 parts by mass or less relative to 100 parts by mass of the antireflective coating. If the content of the organic solvent is less than 5 parts by mass, it may be difficult to form a thin antireflective film. In addition, when applying with a spray gun, the discharge part of the spray gun may be clogged. On the other hand, if the content of the organic solvent exceeds 80 parts by mass, the adhesion to the substrate may be deteriorated. In addition, sagging may occur when applying with a spray gun.

[0032] The preferred viscosity of the anti-reflective coating is 10 mPa·s or more and 200 mPa·s or less. If the viscosity of the anti-reflective coating is less than 10 mPa·s, the adhesion between the substrate and the anti-reflective coating may deteriorate. On the other hand, if the viscosity is greater than 200 mPa·s, it may be difficult to form a thin anti-reflective coating.

[0033] (Additives) The anti-reflective coating material of the present invention may further contain additives, such as dispersants, curing agents, curing catalysts, plasticizers, thixotropic agents, leveling agents, infrared-transmitting organic colorants, infrared-transmitting inorganic colorants, preservatives, ultraviolet absorbers, antioxidants, coupling agents, etc. Also, fillers for the purpose of coloring and matting may be mixed.

[0034] (Surface treatment of irregular fibers) In the anti-reflective coating of the present invention, in order to improve the dispersibility of the irregular fibers, it is possible to apply a coating treatment to the surface of the irregular fibers. For the coating treatment, surfactants, inorganic salts, and various resins can be used.

[0035] For example, the surface of the irregular fibers cut to a desired length is treated with a tannin compound, tartar emetic, etc. to generate the tannin compound, etc. on the fiber surface. This makes good use of the water retention of the tannin compound, etc. to maintain good electrical conductivity on the flock surface. Alternatively, inorganic salts, inorganic silicon compounds, surfactants, and mixtures thereof are attached to the surface of the irregular fibers.

[0036] Examples of tannin compounds include natural tannins and synthetic tannins. Examples of inorganic salts include sodium chloride (NaCl), barium chloride (BaCl2), and magnesium chloride (MgCl2). Examples of magnesium sulfate (MgSO4), sodium silicate (Na2SiO3), sodium carbonate (Na2CO3), and sodium sulfate (Na2SO4) are also included. Examples of inorganic silicon compounds include colloidal silica and the like. Examples of surfactants include anionic surfactants, nonionic surfactants, amphoteric surfactants, and cationic surfactants.

[0037] (Anti-reflective coating manufacturing method) The method for producing the anti-reflective coating material of the present invention is not particularly limited as long as the irregular fibers can be dispersed in the anti-reflective coating material. For example, a bead mill, a ball mill, a jet mill, a three-roll mill, a planetary rotating device, a mixer, an ultrasonic disperser, etc. can be used.

[0038] <Optical components> FIG. 3 is a diagram showing an example of an embodiment of the optical member of the present invention.

[0039] The optical member 10 has an anti-reflection film 12 provided on a substrate 11, and the anti-reflection film 12 is formed from the anti-reflection coating material of the present invention. The anti-reflection film 12 has a resin layer 4 and a non-circular fiber 1 bonded to the resin layer 4. Here, the non-circular fiber 1 is the non-circular fiber explained in Figures 1 and 2, and has a core portion and a plurality of convex portions extending from the core portion.

[0040] The anti-reflection film 12 can diffuse light that is incident between the two convex portions because the tips of the convex portions of the irregular fiber 1 protrude from the resin surface of the resin layer 4. In addition, as shown in Fig. 3, the irregular fiber 1 is bonded to the resin layer 4 via multiple convex portions. Therefore, compared to when spherical particles are bonded to the resin layer, the contact area between the irregular fiber 1 and the resin layer 4 is large, so the irregular fiber 1 is less likely to peel off from the resin layer 4.

[0041] The material of the substrate 11 is not particularly limited, and examples of the metal include aluminum, titanium, stainless steel, magnesium alloy, etc. Also, examples of the plastic include polycarbonate resin, acrylic resin, ABS resin, fluororesin, etc.

[0042] The content of the irregular fibers contained in the anti-reflection film 12 is preferably 33 parts by mass or more and 67 parts by mass or less with respect to 100 parts by mass of the anti-reflection film. If the content of the irregular fibers is less than 33 parts by mass, there is a risk that the anti-reflection function is not sufficiently obtained. On the other hand, if the content is more than 67 parts by mass, the amount of solid content such as resin is small, so that the bonding between the resin layer and the irregular fibers is insufficient, and the irregular fibers may easily fall off.

[0043] The thickness of the anti-reflection film 12 is not particularly limited, but is preferably 10 μm to 500 μm, more preferably 20 μm to 200 μm. If the thickness of the anti-reflection film is thinner than 10 μm, the anti-reflection film may not have sufficient concealing properties. If the thickness of the anti-reflection film exceeds 500 μm, the anti-reflection film may have large thickness unevenness, which may cause peeling. In order to increase the film thickness, it is also possible to apply the film in multiple steps rather than applying it in one go.

[0044] In order to improve the adhesion between the substrate 11 and the anti-reflection film 12, a primer layer may be provided between the substrate 11 and the anti-reflection film 12. Any material may be used for the primer layer, and examples thereof include epoxy resin, urethane resin, acrylic resin, silicone resin, and fluororesin.

[0045] The thickness of the primer layer is preferably from 2 μm to 30 μm, and more preferably from 5 μm to 20 μm. If the thickness is less than 2 μm, the adhesion may be insufficient, and if it exceeds 30 μm, the thickness precision of the antireflection film 12 may be adversely affected.

[0046] (Anti-reflection film manufacturing method) The method for producing the anti-reflective coating is not particularly limited, and examples thereof include brush coating, spray coating, dip coating, transfer coating, etc. Among these, spray coating is preferred from the viewpoint of excellent conformability to the substrate shape.

[0047] The method for curing the anti-reflective coating is not particularly limited, and the coating may be dried at room temperature, curing may be accelerated by heat, or ultraviolet light may be applied.

[0048] <Optical equipment> Fig. 4 shows the configuration of a single-lens reflex digital camera, which is an example of a preferred embodiment of the imaging device of the present invention. In Fig. 4, a camera body 602 and a lens barrel 601, which is an optical device, are connected, and the lens barrel 601 is a so-called interchangeable lens that can be attached to and detached from the camera body 602.

[0049] Light from a subject passes through an optical system consisting of multiple lenses 603, 605, etc. arranged on the optical axis of the photographing optical system inside a housing 620 of the lens barrel 601, and is received by an image sensor 610. Here, the lens 605 is supported by an inner cylinder 604, and is supported movably with respect to the outer cylinder of the lens barrel 601 for focusing and zooming. The inner cylinder 604 is a support body that supports the lens 605.

[0050] During an observation period before shooting, light from a subject is reflected by a main mirror 607 in a housing 621 of the camera body, passes through a prism 611, and then a shot image is projected to the photographer through a 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 a sub-mirror 608 in the direction of an AF (autofocus) unit 613, and this reflected light is used, for example, for distance measurement. The main mirror 607 is attached and supported by a main mirror holder 640 by adhesive or the like. During shooting, the main mirror 607 and the sub-mirror 608 are moved out of the optical path via a driving mechanism (not shown), a shutter 609 is opened, and a shooting light image incident from the lens barrel 601 is formed on an image sensor 610. The aperture 606 is configured so that the brightness and focal depth during shooting can be changed by changing the opening area.

[0051] The optical member of the present invention can be used in imaging devices and optical instruments by forming an anti-reflection film 630 on the base material of the housing 620 and the inner cylinder 604.

[0052] The material of the housing 620 is not particularly limited, and examples of the metal include aluminum, titanium, stainless steel, magnesium alloy, etc. Also, examples of the plastic include polycarbonate resin, acrylic resin, ABS resin, fluororesin, etc.

[0053] The optical device of the present invention has an anti-reflection coating inside the housing that has a low reflectance even at a large angle of incidence, so that an image captured using an imaging device having the optical device of the present invention and an imaging element can have a sufficiently low probability of occurrence of flare or ghosting.

[0054] <Evaluation method> (reflectance measurement) The reflectance was measured using an optical member having an anti-reflection film on a surface of ABS resin measuring 150 mm×70 mm.

[0055] The reflectance of the optical member was measured at wavelengths of 500 nm to 600 nm at an incident angle of 85° every 1 nm using an ultraviolet-visible-near infrared spectrophotometer (manufactured by JASCO Corporation, product name: V-770), and the average value was taken as the reflectance. Note that the measurement was performed after background correction.

[0056] (Strength of anti-reflective coating) The strength of the anti-reflective coating was evaluated by a tape test in accordance with JIS Z 1522. The reflectance of the anti-reflective coating was measured before and after the tape test. Those whose reflectance difference before and after the test was within 0.03% were rated as A, and those whose reflectance difference was greater than 0.03% were rated as B. EXAMPLES

[0057] Example 1 <Creating anti-reflective paint> First, a non-circular fiber A-1 (manufactured by Teijin Frontier Co., Ltd., product name: Octa) having a cross-sectional shape as shown in FIG. 1(c) was prepared. The non-circular fiber A-1 was made of polyester, had a thickness T of 25 μm, a core diameter of 12.5 μm, eight convex portions, and a length C L is 6.25μm, thickness C T is 3 μm.

[0058] Next, the irregular fiber A-1 was cut into lengths of 1 mm using a cutter, i.e., the aspect ratio, which is the ratio of the length to the thickness of the irregular fiber A-1, was 40. After cutting, the irregular fiber A-1 was dyed with a black dye.

[0059] The irregular fiber A-1 and acrylic resin were mixed in a beaker with a thinner, which is an organic solvent, so that the amount of the cut irregular fiber A-1 was 50 parts by mass relative to 100 parts by mass of the paint solid content. In order to adjust the color, a matte material or a colorant such as carbon black may be added separately. A stirrer was used for mixing, and the mixture was stirred at room temperature (23°C) at a speed of 200 rpm for 60 minutes to obtain the anti-reflective paint of Example 1.

[0060] <Creating optical components> Next, the anti-reflective coating material of Example 1 was applied to a surface of the ABS resin measuring 150 mm×70 mm using a spray gun (manufactured by Anest Iwata Corporation, product name: W-200).

[0061] Thereafter, the ABS resin coated with the anti-reflective coating was placed in a constant temperature drying oven at 100° C. and dried for 120 minutes to form an anti-reflective film with a thickness of 70 μm, thereby obtaining the optical component of Example 1 as shown in Fig. 3. When the obtained optical component was observed with a scanning electron microscope, it was confirmed that the tips of the convex portions of the irregular fibers protruded from the surface of the resin layer of the anti-reflective film.

[0062] <Evaluation of optical components> The reflectance of the optical member of Example 1 was evaluated to be 0.12%. Furthermore, the strength of the optical member of Example 1 was evaluated to be A since there was no difference in reflectance before and after the tape test.

[0063] (Examples 2 to 44) In Examples 2 to 44, the type, length, aspect ratio, and content relative to the resin of the irregular fiber were changed as shown in Tables 1 and 2, and anti-reflection coating materials and optical members were obtained in the same manner as in Example 1. When the obtained optical members were observed with a scanning electron microscope, it was confirmed that the tips of the convex portions of the irregular fiber protruded from the surface of the resin layer of the anti-reflection film in all optical members. The evaluation results of each Example are summarized in Table 3.

[0064] The types of irregular fibers are as follows: (A-1) Hollow 8-fin fiber Cross-sectional shape: Fig. 1(c), Material: Polyester, Thickness T: 25 μm, Core diameter: 12.5 μm, Convex parts: 8, Convex part length C L : 6.25μm, thickness of convex part C T : 3μm (A-2) hollow 8-fin fiber Cross-sectional shape: Fig. 1(c), Material: Polyester, Thickness T: 50 μm, Core diameter: 25 μm, Convex parts: 8, Convex part length C L : 12.5μm, thickness of convex part C T : 6μm (A-3) Y-shaped nylon fiber Cross-sectional shape: Fig. 2(a), Material: rayon, Thickness T: 20 μm, Core diameter: 3 μm, Convex parts: 3, Convex part length C L : 9.9μm, thickness of convex part C T : 2.5μm (A-4) crimped fiber Cross-sectional shape: Fig. 2(d)(e), Material: Polyester, Thickness T: 10 μm, Core diameter: 5 μm, Convex parts: 4, Convex part length C L : 2.5μm, thickness of convex part C T : 2μm (A-5) spherical nylon fiber Cross-sectional shape: perfect circle, material: nylon, thickness T: 10 μm, protrusions: none

[0065] [Table 1]

[0066] [Table 2]

[0067] [Table 3]

[0068] Comparative Example 1 <Creating anti-reflective paint> First, spherical fiber A-5 having a perfectly circular cross-sectional shape was prepared. The spherical fiber A-5 was made of nylon and had a thickness T of 10 μm. In other words, the cross-sectional diameter was 10 μm.

[0069] Next, the spherical fiber A-5 was dyed with a black dye and then cut into pieces of 1 mm length using a cutter. In other words, the aspect ratio, which is the ratio of the length to the thickness of the spherical fiber A-5, was 100.

[0070] The spherical fiber A-5 and acrylic resin were mixed in a beaker with a thinner, which is an organic solvent, so that the amount of the cut spherical fiber A-5 was 50 parts by mass per 100 parts by mass of the paint solid content. In addition, a matte material or a colorant such as carbon black may be added separately to adjust the color. A stirrer was used for mixing, and the mixture was stirred at room temperature (23°C) at a speed of 200 rpm for 60 minutes to obtain the anti-reflective paint of Comparative Example 1.

[0071] <Creating optical components> Next, the anti-reflective coating material of Comparative Example 1 was applied to a surface of the ABS resin measuring 150 mm×70 mm using a spray gun (manufactured by Anest Iwata Corporation, product name: W-200).

[0072] Thereafter, the ABS resin coated with the anti-reflective coating was placed in a constant temperature drying oven set at 100° C. and dried for 120 minutes to form an anti-reflective film with a thickness of 70 μm, thereby obtaining an optical component of Comparative Example 1 as shown in FIG. 3.

[0073] <Evaluation of optical components> The reflectance of the optical member of Comparative Example 1 was evaluated and found to be 0.35%.

[0074] Furthermore, when the strength of the optical member of Comparative Example 1 was evaluated, the reflectance did not differ between before and after the tape test, and therefore the optical member was rated as A.

[0075] (Comparative Examples 2 to 12) In Comparative Examples 2 to 12, the type, length, aspect ratio, and content relative to the resin of the non-circular fiber were changed as shown in Table 4, and anti-reflection coatings and optical members were obtained in the same manner as in Comparative Example 1. The evaluation results of each Comparative Example are summarized in Table 5.

[0076] [Table 4]

[0077] [Table 5]

[0078] According to the results of the Examples and Comparative Examples, the reflectance of Examples 1 to 44 using irregular fibers was good at less than 0.20%, whereas the reflectance of Comparative Examples 1 to 12 using spherical particles was higher than 0.2%.

[0079] Furthermore, among the Examples, Examples 1 to 16 and Examples 21 to 44, in which the content of the irregular fiber was 50 parts by mass or more, had lower reflectance than Examples 17 to 20, in which the content of the irregular fiber was 43 parts by mass.

[0080] Furthermore, among the Examples, Examples 1 to 36 in which the length of the convex portion of the irregular fiber was 6.25 μm or more had a lower reflectance than Examples 37 to 44 in which the length of the convex portion was 2.5 μm.

[0081] In addition, the reflectance of Comparative Example 12 was lower than those of Comparative Examples 1 to 11, but peeling of the spherical particles was visually confirmed by the tape test, and the change in reflectance before and after the tape test was large at 0.04%. This is considered to be due to the fact that the content of the spherical particles was high at 69 parts by mass. [Explanation of symbols]

[0082] 1. Special fiber 2 Nucleus 3 Convex 4 Resin layer 11 Base material 12 Anti-reflection coating 21 Hole 600 Imaging device 601 Optical equipment 604 Support 620 Case 630 Anti-reflection coating

Claims

1. An anti-reflective film comprising a black resin layer having a surface and a black irregular fiber, The irregular fiber has a core and three or more protrusions extending from the core, The convex portion is arranged on the periphery in a cross section perpendicular to the longitudinal direction of the irregular fiber, a tip of the protrusion protrudes from a surface of the resin layer, The length of the protrusion is 2.5 μm or more and 20 μm or less, The content of the irregular fibers is 33 parts by mass or more and 67 parts by mass or less per 100 parts by mass of the antireflection film.

2. An anti-reflective film comprising a black resin layer having a surface and a black irregular fiber, The irregular fiber has a core and three or more protrusions extending from the core, The convex portion is arranged on the periphery in a cross section perpendicular to the longitudinal direction of the irregular fiber, a tip of the protrusion protrudes from a surface of the resin layer, The length of the protrusion is 2.5 μm or more and 20 μm or less, An anti-reflection film, characterized in that the content of the irregular fibers is 50 parts by mass or more and 200 parts by mass or less per 100 parts by mass of the anti-reflection film excluding the irregular fibers.

3. 3. The anti-reflection film according to claim 1, wherein the aspect ratio, which is the ratio of the length of the irregular fiber to the thickness of the cross section in a direction perpendicular to the length direction of the irregular fiber, is 4 or more and 100 or less.

4. 4. The anti-reflection coating according to claim 1, wherein the length of the irregular fibers is 0.2 mm or more and 1.0 mm or less.

5. 5. The anti-reflection coating according to claim 1, wherein the thickness of the convex portion is from 2 [mu]m to 6 [mu]m.

6. 6. The anti-reflection coating according to claim 1, wherein the thickness of the irregular fibers is 10 μm or more and 50 μm or less.

7. 7. The anti-reflection coating according to claim 1, wherein the number of the convex portions is eight or less.

8. 8. The anti-reflection film according to claim 1, wherein the resin layer has a thickness of 10 μm or more and 500 μm or less.

9. 9. The anti-reflection coating according to claim 1, wherein the resin constituting the resin layer is at least one of an acrylic resin, a urethane resin, and an epoxy resin.

10. 10. An optical member comprising a substrate and an antireflection film provided on the substrate, the antireflection film being the antireflection film according to claim 1.

11. 11. The optical member according to claim 10, wherein the substrate comprises at least one selected from the group consisting of aluminum, titanium, stainless steel, a magnesium alloy, a polycarbonate resin, an acrylic resin, an ABS resin, and a fluororesin.

12. The optical member according to claim 10 or 11, further comprising a primer layer between the substrate and the antireflection film.

13. An optical instrument having a housing and an optical system having at least one lens within the housing, an anti-reflection film is formed on a support supporting the lens and / or an inner wall surface of the housing, 10. An optical device, comprising the anti-reflection film according to claim 1.

14. An imaging device comprising: a housing; an optical system having at least one lens in the housing; and an imaging element that receives light that has passed through the optical system, an anti-reflection film is formed on a support supporting the lens and / or an inner wall surface of the housing, An imaging device, wherein the antireflection film is the antireflection film according to claim 1 .

15. The imaging device of claim 14, wherein the imaging device is a camera.

16. An anti-reflective coating comprising a black irregular fiber, a black resin, and an organic solvent, The irregular fiber has a core and three or more protrusions extending from the core, The convex portion is arranged on the periphery in a cross section perpendicular to the longitudinal direction of the irregular fiber, The length of the protrusion is 2.5 μm or more and 20 μm or less, An anti-reflective coating material, characterized in that the content of the irregular fibers is 33 parts by mass or more and 67 parts by mass or less per 100 parts by mass of the paint solid content.

17. An anti-reflective coating comprising a black irregular fiber, a black resin, and an organic solvent, The irregular fiber has a core and three or more protrusions extending from the core, The convex portion is arranged on the periphery in a cross section perpendicular to the longitudinal direction of the irregular fiber, The length of the protrusion is 2.5 μm or more and 20 μm or less, An anti-reflective coating material characterized in that the content of the irregular fibers is 50 parts by mass or more and 200 parts by mass or less per 100 parts by mass of the coating solids excluding the irregular fibers.

18. 18. The anti-reflective coating according to claim 16 or 17, characterized in that the aspect ratio, which is the ratio of the length of the irregular fiber to the thickness of the cross section in a direction perpendicular to the length direction of the irregular fiber, is 4 or more and 100 or less.

19. 19. The anti-reflective coating material according to any one of claims 16 to 18, wherein the length of the irregularly shaped fibers is 0.2 mm or more and 1.0 mm or less.

20. 20. The anti-reflective coating according to claim 16, wherein the thickness of the convex portion is from 2 μm to 6 μm.

21. 21. The anti-reflective coating according to claim 16, wherein the thickness of the irregular fibers is 10 μm or more and 50 μm or less.

22. 22. The anti-reflective coating according to any one of claims 16 to 21, wherein the number of said convex portions is eight or less.

23. 23. The anti-reflective coating according to any one of claims 16 to 22, wherein the resin is at least one of an acrylic resin, a urethane resin, and an epoxy resin.

24. The anti-reflective coating according to any one of claims 16 to 23, wherein at least one of a tannin compound, an inorganic salt, an inorganic silicon compound, a surfactant, and a mixture thereof is adhered to the surface of the irregular fiber.

25. A step of spraying the anti-reflective coating material according to any one of claims 16 to 24 onto an object; and drying the anti-reflective coating material.

Images