Light-shielding film and lens unit

Abstract

The present invention relates to a light-shielding film comprising a light-shielding substrate and an anti-gloss layer superimposed on the substrate, wherein the anti-gloss layer is more transparent than the substrate, the light-shielding film has an optical density of 4.0 or more at a wavelength of 380 nm to 780 nm, at least one surface of the anti-gloss layer has a gloss of 0.0% to 10.0% at an incident angle of 60 degrees, and the surface resistivity of the light-shielding film is 1.0 × 10⁵ Ω / □ or less.

Description

[Technical Field]

[0001] This invention relates to a light-shielding film and a lens unit. [Previous Technology]

[0002] Light-shielding components are used as shutter, aperture, or gap adjustment components between multiple lenses in optical parts such as smartphones or digital video cameras. For example, light-shielding components are manufactured using a light-shielding film having a sheet-like substrate and a light-shielding layer superimposed on the surface of the substrate. For example, Patent Document 1 discloses a light-shielding film that is essentially composed of an organic resin and a black material, characterized in that the organic resin contains a curable resin curing agent or a thermoplastic resin with a glass transition temperature of 150°C or higher. However, this type of light-shielding film has the disadvantage of having a relatively high reflectivity.

[0003] On the other hand, Patent Document 2 discloses a light-shielding film comprising a sheet-like substrate with light-shielding properties and an anti-gloss layer. The anti-gloss layer is overlapped on the substrate, has an uneven surface formed on the side opposite to the substrate, and is more transparent than the substrate. The anti-gloss layer contains an adhesive resin, filler particles dispersed in the adhesive resin, and a coloring component dispersed in the adhesive resin, and its blackness is within a specified range. By providing the anti-gloss layer, low reflectivity is achieved. [Prior Art Documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2010-534342 [Patent Document 2] Japanese Patent Application Publication No. 2022-137471 [Summary of the Invention]

[0005] The light-shielding film in Patent Document 2 only achieves a specified range of blackness by providing an anti-gloss layer with an uneven surface, without conducting any research on the antistatic function of the light-shielding film. After conducting research, the inventors realized that the antistatic function of the light-shielding film in Patent Document 2 is low, and due to the influence of static electricity, it will adhere to unexpected locations, resulting in low workability. Workability refers to the characteristic of being able to easily place the light-shielding film in the desired position, for example, when it is used in the shutter of an optical component.

[0006] The object of the present invention is to provide a light-shielding film that combines low reflectivity and workability. Furthermore, the object of the present invention is to provide a lens unit incorporating the light-shielding film of the present invention.

[0007] This invention relates to the following: [1] A light-shielding film comprising a light-shielding substrate and an anti-gloss layer superimposed on the substrate, the anti-gloss layer being more transparent than the substrate, the light-shielding film having an optical density of 4.0 or more at a wavelength of 380 nm to 780 nm, at least one surface of the anti-gloss layer having a gloss of 0.0% to 10.0% at an incident angle of 60 degrees, and a surface resistivity of 1.0 × 10⁵ Ω / □ or less. [2] The light-shielding film as described in [1], wherein the substrate has antistatic properties. [3] The light-shielding film as described in [1] or [2], wherein the substrate contains carbon black. [4] The light-shielding film as described in any one of [1] to [3], wherein the anti-gloss layer contains carbon black, and the content of the carbon black in the anti-gloss layer is greater than 0% by mass and less than 5% by mass. [5] The light-shielding film described in any one of [1] to [4], wherein the anti-gloss layer contains an adhesive resin and particles dispersed within the adhesive resin. [6] The light-shielding film described in any one of [1] to [5], wherein the thickness of the light-shielding film is 35 μm or less. [7] The light-shielding film described in any one of [1] to [6], wherein the thickness of the substrate is 2 μm or more and 30 μm or less. [8] The light-shielding film described in any one of [1] to [7], wherein the thickness of the anti-gloss layer is 1 μm or more and 7 μm or less. [9] The light-shielding film described in any one of [1] to [8] is disposed on a shutter, aperture component, or gap adjustment component between a plurality of lenses of an optical component.

[10] A lens unit comprising the light-shielding film described in [9].

[0008] According to the present invention, a light-shielding film that combines low reflectivity and workability is provided. Furthermore, a lens unit incorporating the light-shielding film of the present invention is provided.

Implementation Method

[0010] Hereinafter, the present invention will be described based on specific embodiments. Furthermore, in this specification, when the lower limit and upper limit of a numerical range are described separately, the numerical range can be set as any combination of any lower limit and any upper limit among them. In the present invention, the numerical range represented by "A to B" means a numerical range containing both a lower limit and an upper limit. In the present invention, Ω / □, the unit of surface resistance, is represented as Ω / square.

[0011] The light-shielding film of the present invention comprises a light-shielding substrate and an anti-gloss layer superimposed on the substrate. Furthermore, the anti-gloss layer is more transparent than the substrate. Moreover, the optical density of the light-shielding film at wavelengths of 380 nm to 780 nm is 4.0 or higher. Furthermore, at least one surface of the anti-gloss layer has a gloss level of 0.0% to 10.0% at an incident angle of 60 degrees. In addition, the surface resistivity of the light-shielding film is 1.0 × 10⁵ Ω / □ or lower.

[0012] As described above, the substrate has light-blocking properties, and the anti-gloss layer is more transparent than the substrate. This allows the light-blocking properties of the substrate to be utilized externally via the anti-gloss layer. As a result, a light-blocking film with low brightness and excellent light-blocking properties is obtained. Furthermore, a light-blocking film with an optical density value of 4.0 or higher at wavelengths between 380 nm and 780 nm indicates high blackness; the film is jet black, indicating excellent light-blocking properties. Moreover, at least one surface of the anti-gloss layer has a gloss level of 0.0% to 10.0% at an incident angle of 60 degrees, indicating excellent anti-gloss properties. This makes it easy to reduce the reflectivity of the light-blocking film. Next, a surface resistivity value of 1.0 × 10⁵ Ω / □ or lower indicates high antistatic properties. This makes it easy to obtain a light-blocking film with excellent workability. The light-shielding film of the present invention can be used as a shutter, aperture component, or gap adjustment component between multiple lenses in optical components.

[0013] FIG1 is a cross-sectional view of a light-shielding film 100 according to one embodiment of the present invention. The light-shielding film 100 includes a light-shielding substrate 101 and an anti-gloss layer 102 overlapped on the substrate. In FIG1, a first anti-gloss layer and a second anti-gloss layer are provided on two area layers of the substrate 101, but an anti-gloss layer may also be provided only on a single area layer of the light-shielding substrate 101. Hereinafter, the layers that can constitute the light-shielding film will be described.

[0014] (Substrate) The substrate supports the anti-gloss layer. The substrate may be a single layer or have multiple layers. When the substrate is a single layer, the material used in the substrate is not particularly limited, but preferably contains resin and colorant. The resin is not particularly limited, but preferably is one or more resins selected from the group consisting of polyethylene terephthalate (PET), polyimide (PI), polyvinyl chloride (PVC), polypropylene (PP), polystyrene (PS), polycarbonate (PC), and ethylene-methacrylic acid copolymer (EMAA), more preferably PET.

[0015] When the substrate is a single layer and contains resin, the resin content in the substrate is not particularly limited, but is preferably 50% by mass or more and 100% by mass or less, and more preferably 60% by mass or more and 100% by mass or less.

[0016] There are no particular limitations on the colorant used; for example, carbon black can be used. There are no particular limitations on the carbon black used; for example, conductive carbon black such as furnace black, thermal black, lamp black, acetylene black, or Ketjen black can be used. From the viewpoint of adjusting the surface resistivity of the substrate, conductive particles such as conductive carbon black are preferred as the colorant, and conductive carbon black is even more preferred. Specifically, examples of conductive carbon black include DENKA BLACK (registered trademark) (manufactured by DENKA Corporation), Ketjen black EC (manufactured by Lion Specialty Chemicals Corporation), and Ketjen black EC-600D (manufactured by Lion Specialty Chemicals Corporation). Furthermore, dispersions of conductive carbon black can also be used; for example, MHI BLACK#273 (manufactured by Mikoku Pigment Corporation).

[0017] When the substrate is a single layer and contains a colorant, the content of the colorant in the substrate is not particularly limited, but it is preferably greater than 0% by mass and less than 50% by mass, and more preferably more than 1% by mass and less than 40% by mass. If it is within the above range, the light-blocking properties of the substrate are good.

[0018] When the substrate is a single layer and contains a colorant, and the colorant is carbon black, the content of carbon black in the substrate is not particularly limited. It is preferably greater than 0% by mass and less than 50% by mass, more preferably more than 1% by mass and less than 40% by mass, further preferably more than 10% by mass and less than 40% by mass, and even more preferably more than 25% by mass and less than 40% by mass. If it is within the above range, the conductivity of the substrate is better, and the surface resistance value of the light-shielding film is more likely to fall within the range described later.

[0019] Furthermore, as described above, the substrate has light-shielding properties. Here, "having light-shielding properties" means that the optical density value of the substrate, as described later, is 2.0 or higher. Also, the optical density value of the substrate is preferably 3.0 or higher, more preferably 4.0 or higher. There is no particular upper limit; it can be 3.0 or higher and 10.0 or lower, or 4.0 or higher and 10.0 or lower. By using a light-shielding material as the material for the substrate, a light-shielding substrate can be obtained. For example, metal foils such as aluminum foil or substrates containing colorants can become light-shielding substrates. Furthermore, by having a plurality of layers in the substrate, and one or more of the plurality of layers having light-shielding properties, a light-shielding substrate can be manufactured. The state of a substrate having a plurality of layers will be described below.

[0020] The substrate may contain conductive particles other than conductive carbon black. There are no particular limitations on such conductive particles; for example, particles of metals such as gold, silver, copper, and nickel can be used. By containing the aforementioned conductive particles, it is easy to adjust the surface resistivity of the substrate to the range described later. The content of conductive particles other than conductive carbon black in the substrate is not particularly limited, but it is preferably greater than 0% by mass and less than 50% by mass, more preferably more than 1% by mass and less than 40% by mass, further preferably more than 10% by mass and less than 40% by mass, and even more preferably more than 25% by mass and less than 40% by mass. If it is within the above range, the conductivity of the substrate becomes better, and the surface resistivity of the light-shielding film easily falls within the range described later.

[0021] The substrate may contain other materials, including antioxidants, UV absorbers, heat stabilizers, plasticizers, lubricants, flame retardants, and other additives. The shape of the substrate is not particularly limited; for example, a film-like form is preferred. Furthermore, the thickness of the substrate is not particularly limited; for example, it may be 2 μm to 30 μm, 2 μm to 20 μm, or 5 μm to 15 μm.

[0022] The substrate preferably has antistatic properties. Antistatic properties of the substrate facilitate improved workability. Antistatic properties mean that the surface resistivity of the substrate is 1.0 × 10¹¹ Ω / □ or less. Furthermore, the surface resistivity of the substrate is more preferably 1.0 × 10¹⁰ Ω / □ or less, more preferably 1.0 × 10⁹ Ω / □ or less, particularly preferably 1.0 × 10⁷ Ω / □ or less, and especially preferably 1.0 × 10⁶ Ω / □ or less. If it falls within the above range, it is easier to adjust the surface resistivity of the light-shielding film to the range described later. The lower limit is not specifically limited and can be 1.0×10⁻³~1.0×10¹¹ Ω / □, 1.0×10⁻²~1.0×10¹⁰ Ω / □, 1.0×10⁻¹~1.0×10⁹ Ω / □, 1.0×10⁰~1.0×10⁷ Ω / □, or 1.0×10¹~1.0×10⁶ Ω / □. The surface resistivity of the substrate can be adjusted by changing the type and content of the material used in the substrate. For example, if the substrate contains conductive particles, it is easy to adjust the surface resistivity of the substrate to the above range. Furthermore, when the substrate with light-shielding properties contains conductive particles, the surface resistivity can be reduced by increasing the content of conductive particles in the substrate or by using conductive particles with higher conductivity, and the surface resistivity can be increased by reducing the content of conductive particles or by using conductive particles with low conductivity. The method for measuring the surface resistivity of the substrate will be described below.

[0023] (Anti-gloss layer) The anti-gloss layer 102 is more transparent than the substrate 101. This greater transparency of the anti-gloss layer 102 compared to the substrate 101 can be confirmed by measuring the total light transmittance of the anti-gloss layer 102 and the substrate 101. That is, when the total light transmittance of the anti-gloss layer 102 is higher than the total light transmittance of the substrate 101, the anti-gloss layer 102 can be considered more transparent than the substrate 101. Total light transmittance refers to the transmittance measured according to the method in JIS K 7375:2008. The total light transmittance of the substrate and the anti-gloss layer can be adjusted by changing the type and content of the materials used. For example, if the amount of colorant that the anti-gloss layer can contain is less than the amount of colorant that the substrate can contain, it is easy to make the total light transmittance of the anti-gloss layer higher than the total light transmittance of the substrate.

[0024] An anti-gloss layer 102 is overlapped and disposed on a substrate 101. The anti-gloss layer 102 is a layer that scatters light incident on the light-shielding film 100 to prevent gloss from the light-shielding film 100. There is no particular limitation on whether the anti-gloss layer 102 can prevent the gloss of the light-shielding film. It is preferable that the anti-gloss layer 102 has an uneven surface formed on the surface opposite to the substrate 101. If such an uneven surface is formed, it is easier to prevent the gloss of the light-shielding film. There is no particular limitation on the method of forming the uneven surface. For example, the following known means can be used: a method of containing the particles described later in the anti-gloss layer; a method of transferring the uneven pattern to the anti-gloss layer; a method of containing a plurality of adhesive resins in the anti-gloss layer to form a phase-separated structure, etc. Here, the phase-separated structure can be formed, for example, by the hydrocyclohexane decomposition (wet hydrocyclohexane decomposition) of the liquid phase from the coating liquid used to form the anti-gloss layer. For details on the phase-separated structure, please refer to Japanese Publication No. 6190581.

[0025] The material used for the anti-gloss layer is not particularly limited, but preferably contains an adhesive resin and a colorant. The adhesive resin is not particularly limited, and may be selected from one or more resins grouped together with thermoplastic resins, thermosetting resins, and photocuring resins. When the anti-gloss layer contains an adhesive resin, the content of the adhesive resin in the anti-gloss layer is not particularly limited, but preferably is 40% by mass or more and 100% by mass or less, more preferably 50% by mass or more and 90% by mass or less.

[0026] Examples of thermoplastic resins include: polyolefins, styrene resins, acrylic resins, vinyl chloride resins, polyvinyl alcohol resins, polyacetal resins, saturated polyester resins, polycarbonate resins, polyamide resins, polyimide resins, polyurethane resins, polyphenylene ether resins, polyphenylene sulfide resins, fluoropolymers, cellulose derivatives, thermoplastic polyurethane resins, etc.

[0027] Examples of thermosetting resins include: phenolic resins, melamine resins, urea resins, guanidine resins, silicone resins, epoxy resins, unsaturated polyester resins, vinyl ester resins, and thermosetting polyurethane resins. Examples of thermosetting polyurethane resins include: urethane resins or urethane acrylic resins. Among these, urethane acrylic resins are preferred.

[0028] Examples of photocurable resins include photocurable polyester resins, photocurable acrylic resins, photocurable epoxy (meth)acrylate resins, and photocurable amine (meth)acrylate resins. The term "photocurable" here refers to the property of monomers to polymerize and harden using light of a specific wavelength.

[0029] There are no particular limitations on the colorant used; for example, carbon black can be used. As for the carbon black, those described in the substrate description can be used. From the viewpoint of adjusting the surface resistivity of the light-shielding film, conductive particles such as conductive carbon black are preferred, and conductive carbon black is even more preferred. When the anti-gloss layer contains carbon black, the content of carbon black in the anti-gloss layer is not particularly limited, but it is preferably greater than 0% by mass and less than 5% by mass, and more preferably more than 2% by mass and less than 5% by mass. If it falls within the above range, the optical density value of the light-shielding film will easily fall within the range described later.

[0030] The anti-gloss layer preferably contains an adhesive resin and particles dispersed within the adhesive resin. This facilitates the formation of unevenness on the surface of the anti-gloss layer, thus easily preventing the gloss of the light-blocking film. The particles are not particularly limited, and examples include particles of the aforementioned colorant, silicon dioxide particles, inorganic particles such as the aforementioned metal particles, and organic particles such as resin particles. Silicon dioxide particles are preferred as inorganic particles. Furthermore, the particles may contain conductive particles other than carbon black. The particle content in the anti-gloss layer is not particularly limited, but is preferably 5% by mass or more and 50% by mass or less, more preferably 10% by mass or more and 40% by mass or less.

[0031] The thickness of the anti-gloss layer is not particularly limited, for example, it can be more than 1 μm and less than 10 μm, or more than 1 μm and less than 7 μm.

[0032] As described above, the substrate may have multiple layers. For example, FIG2 is a cross-sectional view of a light-shielding film 100 of one embodiment of the present invention. In FIG2, the light-shielding substrate includes a base layer 103 and a light-shielding layer 104 overlapping the base layer 103. Moreover, the light-shielding film 100 includes a light-shielding substrate and an anti-gloss layer 102 overlapping the base layer. In FIG2, a first light-shielding layer and a second light-shielding layer are present on two area layers of the base layer 103, but a light-shielding layer may also be present only on a single area layer of the base layer 103.

[0033] There are no particular limitations on the material used as the base layer, but it is preferable to contain resin. That is, the base layer is preferably a resin layer. As the resin, the resin listed in the substrate section can be used. When the base layer contains resin, the resin content in the base layer is not particularly limited, but it is preferably 80% by mass or more and 100% by mass or less, more preferably 90% by mass or more and 100% by mass or less. The base layer may contain other materials, and may also contain various additives such as antioxidants, ultraviolet absorbers, heat stabilizers, plasticizers, lubricants, and flame retardants. There are no particular limitations on the thickness of the base layer, for example, it may be 1 μm or more and 10 μm or 1 μm or more and 7 μm or less.

[0034] The material used as the light-shielding layer is not particularly limited, but it preferably contains an adhesive resin and a colorant. As the adhesive resin, the adhesive resin described in the section on the anti-gloss layer can be used. Furthermore, as the colorant, the colorants described in the sections on the substrate and the anti-gloss layer can be used. From the viewpoint of adjusting the surface resistivity of the substrate, conductive particles such as conductive carbon black are preferred, and conductive carbon black is even more preferred. The light-shielding layer may contain the aforementioned conductive particles other than conductive carbon black.

[0035] From the viewpoint of improving the compatibility between the substrate and the anti-gloss layer, when both the light-shielding layer and the anti-gloss layer contain adhesive resins, it is preferable that the adhesive resin contained in the light-shielding layer and the adhesive resin contained in the anti-gloss layer are of the same type. For example, it is preferable that the adhesive resin contained in the light-shielding layer is an urethane acrylic resin, and the adhesive resin contained in the anti-gloss layer is an urethane acrylic resin. Furthermore, it is even more preferable that the adhesive resin contained in the light-shielding layer and the adhesive resin contained in the anti-gloss layer are the same.

[0036] From the viewpoint of improving the compatibility between the substrate and the anti-gloss layer, when both the light-shielding layer and the anti-gloss layer contain colorants, it is preferable that the colorants contained in the light-shielding layer and the anti-gloss layer are of the same type. For example, it is preferable that both the light-shielding layer and the anti-gloss layer contain carbon black as the colorant. Furthermore, it is even more preferable that the colorants contained in the light-shielding layer and the anti-gloss layer are the same.

[0037] When the light-shielding layer contains adhesive resin, the content of adhesive resin in the light-shielding layer is not particularly limited, but preferably it is 50% by mass or more and 100% by mass or less, more preferably 60% by mass or more and 90% by mass or less. When the light-shielding layer contains carbon black, the content of carbon black in the light-shielding layer is not particularly limited, but preferably it is greater than 0% by mass and less than 50% by mass, more preferably 10% by mass or more and 40% by mass or less, and even more preferably 15% by mass or more and 40% by mass or less. The thickness of the light-shielding layer is not particularly limited, for example, it can be 1 μm or more and 10 μm or more and 5 μm or less.

[0038] As described above, the optical density value of the light-shielding film at wavelengths of 380 nm to 780 nm is 4.0 or higher. Preferably, the optical density value is 5.0 or higher, and more preferably 6.0 or higher. If it falls within the above range, it is easy to obtain a light-shielding film with excellent light-shielding properties. There is no particular upper limit; it can be 4.0 to 10.0 or lower, 5.0 to 10.0 or lower, or 6.0 to 10.0 or lower. The optical density value can be adjusted by changing the type and content of the light-shielding substrate and the material used for the anti-gloss layer. Specifically, by providing the light-shielding film with a light-shielding substrate and an anti-gloss layer, it is easy to make the optical density value fall within the above range. Furthermore, when the light-shielding substrate contains a colorant, increasing the content of the colorant in the substrate can increase the optical density value, and decreasing the content of the colorant can decrease the optical density value. Similarly, when the anti-gloss layer contains colorants, increasing the amount of colorant in the anti-gloss layer can increase the optical density value, while decreasing the amount of colorant can decrease the optical density value. The method for measuring the optical density value will be explained below.

[0039] As described above, at least one surface of the anti-gloss layer has a gloss level of 0.0% to 10.0% at an incident angle of 60 degrees. Preferably, the gloss level is 0.0% to 5.0%, and more preferably 0.0% to 1.0%. If it falls within the above range, the anti-gloss properties of the anti-gloss layer become more excellent. This makes it easier to reduce the reflectivity of the light-blocking film. The gloss level can be adjusted, for example, by adjusting the type and content of the aforementioned particles that may be contained in the anti-gloss layer. Specifically, if inorganic particles such as silicon dioxide particles are used as the aforementioned particles, it is easier to achieve the gloss level within the above range. The method for measuring gloss level will be described below.

[0040] As described above, the surface resistivity of the light-shielding film is 1.0 × 10⁵ Ω / □ or less. Preferably, the surface resistivity of the light-shielding film is 5.0 × 10⁴ Ω / □ or less, more preferably 1.0 × 10⁴ Ω / □ or less. The lower limit is not particularly limited; it can be 1.0 × 10⁻³ Ω / □ or more, or 1.0 × 10⁻² Ω / □ or more, or 1.0 × 10⁻¹ Ω / □ or more. That is, the surface resistivity of the light-shielding film can be, for example, 1.0 × 10⁻³ to 1.0 × 10⁵ Ω / □, 1.0 × 10⁻² to 5.0 × 10⁴ Ω / □, or 1.0 × 10⁻¹ to 1.0 × 10⁴ Ω / □. If it falls within the above range, the antistatic function of the light-shielding film is even better. Therefore, it is easier to make a light-shielding film with excellent workability. The surface resistivity of the light-shielding film can be adjusted by changing the surface resistivity of the substrate according to the method described in the substrate's instructions. Furthermore, by improving the compatibility between the substrate and the anti-gloss layer, it is easier to bring the surface resistivity of the light-shielding film into the aforementioned range. The method for measuring the surface resistivity of the light-shielding film will be explained below.

[0041] Furthermore, the thickness of the light-shielding film is not particularly limited; for example, it can be 35 μm or less, or 30 μm or less. If the thickness of the light-shielding film is within this range, although the workability of the light-shielding film is more easily reduced, if it is the light-shielding film of the present invention, excellent workability can be obtained. The lower limit of the thickness of the light-shielding film is not particularly limited; it can be 3 μm or more but less than 35 μm, 3 μm or more but less than 30 μm, or 8 μm or more but less than 20 μm.

[0042] <Lens Unit> The lens unit includes the light-shielding film of the present invention. For example, the lens unit includes a light-shielding film and a lens. FIG3 is an exploded view of the lens unit 40. In FIG3, the lens unit 40 includes a plurality of light-shielding members F1 to F6, a plurality of optical members (here, lenses L1 to L6), and a housing (lens tube) 41 for housing the light-shielding members F1 to F6 and the optical members. In FIG3, the light-shielding members F1 to F6 are arranged between adjacent optical members in a manner that surrounds the optical axis R of the optical members. The number of light-shielding members and the number of optical members included in the lens unit 40 are not limited.

[0043] The light-shielding members F1 to F6 have the same cross-sectional structure as the light-shielding film. That is, the light-shielding members F1 to F6 have a light-shielding substrate and an anti-gloss layer superimposed on the substrate. The light-shielding substrate can be the one described in the description of the substrate, and the anti-gloss layer can be the one described in the description of the anti-gloss layer. According to the lens unit of the present invention, the anti-glare property of scattering incident light from the outside through the anti-gloss layer can be given to the light-shielding members F1 to F6. Furthermore, the reflection of incident light incident into the anti-gloss layer can be suppressed. In this way, the brightness of the surface of the anti-gloss layer can be effectively reduced. As described above, the anti-gloss layer is more transparent than the substrate. Therefore, the light-shielding property of the substrate can be exerted externally through the anti-gloss layer. As a result, light-shielding members F1 to F6 with low brightness and excellent light-shielding property can be realized.

[0044] Hereinafter, the method for measuring the physical properties of the light-shielding film of the present invention will be described.

[0045] <Method for measuring the optical density of the light-shielding film> The optical density of the light-shielding film at wavelengths above 380 nm and below 780 nm was measured using a transmission densitometer (Xrite's "341C type (transmission densitometer)").

[0046] <Method for measuring the gloss of the anti-gloss layer> The gloss of the anti-gloss layer surface at an incident angle of 60 degrees was measured using a gloss meter (TQC-manufactured "RDK-12 / KT-GL0030 type").

[0047] <Method for Measuring Surface Resistivity> The surface resistivity of the light-shielding substrate surface and the anti-gloss layer surface was measured using a Loresta (Mitsubishi Chemical's "MCP-T610 type"). When the measured value exceeds the upper limit of the Loresta, an ultra-high resistance / micro-ammeter (Advantest Co., Ltd.'s "R8340") was used to measure the surface resistivity and obtain the value. Here, the result obtained from measuring the surface of the anti-gloss layer is taken as the surface resistivity of the light-shielding film.

[0048] Each embodiment and its combination thereof is an example. Without departing from the spirit of the invention, appropriate additions, omissions, substitutions, and other modifications to the components may be made. The invention is not limited to any particular embodiment, but only to the scope of the patent application. [Example]

[0049] Hereinafter, the present invention will be specifically described with reference to embodiments. However, the present invention is not limited to the following embodiments.

[0050] [Example 1] A 6 μm thick PET film (PET film manufactured by Toray Industries, Inc.) was used as the base layer. 32 parts by weight of an amide acrylate resin (KDC-01 main agent manufactured by Kohshin Chemical, Inc.) used as the adhesive resin, 3 parts by weight of an ink containing carbon black and amide acrylate resin (E039 PET AKSB 92T manufactured by TOYOCHEM, Inc.), 55 parts by weight of a carbon black dispersion (MHI BLACK#273 manufactured by Mikuni Pigment, Inc.), and 10 parts by weight of a hardener (Takenate A-3 manufactured by Mitsui Chemicals, Inc.) were added to obtain a coating liquid. The obtained coating liquid was applied to both sides of the base layer, and a pair of light-shielding layers with a dry thickness of 1.5 μm were formed by heat curing, thus obtaining a light-shielding substrate. Furthermore, a coating liquid was obtained by mixing 54 parts by weight of an amide acrylate resin (KDC-01 main agent manufactured by Kohshin Chemical Co., Ltd.) as the adhesive resin, 6 parts by weight of an ink containing carbon black and amide acrylate resin (E039 PET AKSB 92T manufactured by TOYOCHEM Co., Ltd.), 12.5 parts by weight of a hardener (Takenate A-3 manufactured by Mitsubishi Chemical Co., Ltd.), 7.5 parts by weight of silica particles (Sylophobic100 manufactured by Fujisilica Co., Ltd.), 15 parts by weight of a carbon black dispersion (MHI BLACK#273 manufactured by Mikuni Pigment Co., Ltd.), and a solvent (methyl ethyl ketone) as the remainder. The obtained coating liquid was applied to both sides of a light-shielding substrate, and a pair of anti-gloss layers with a thickness of 3.5 μm after drying were formed by thermosetting, thus obtaining a light-shielding film. The obtained light-shielding film was measured using the method described above. The measurement results are shown in Table 1.

[0051] [Example 2] Except that the amount of carbon black dispersion (MHI BLACK #273 manufactured by Mikuni Pigment Co., Ltd.) used to form the light-shielding layer was changed to 30 parts by mass, a light-shielding film was obtained in the same manner as in Example 1. The obtained light-shielding film was measured in the same way as in Example 1. The measurement results are shown in Table 1.

[0052] [Comparative Example 1] The amount of amine acrylate resin used as an adhesive resin in forming the light-shielding layer was set to 38 parts by mass, the amount of ink was set to 52 parts by mass, and carbon black dispersion was not used. Otherwise, a light-shielding film was obtained in the same manner as in Example 1. The obtained light-shielding film was measured in the same way as in Example 1. The measurement results are shown in Table 1.

[0053] [Comparative Example 2] Except that a carbon black mixed black film (manufactured by Nan Ya Plastics Co., Ltd.) with a thickness of 12 μm was used as the substrate with light-shielding properties, and the thickness of the anti-gloss layer after drying was set to 5 μm, a light-shielding film was obtained in the same manner as in Example 1. The obtained light-shielding film was measured in the same way as in Example 1. The measurement results are shown in Table 1.

[0054] [Comparative Example 3] A light-shielding film was obtained in the same manner as in Example 1, except that no anti-gloss layer was formed. That is, a light-shielding substrate was obtained in the same manner as in Example 1, and the obtained substrate was used as a light-shielding film. The obtained light-shielding film was measured in the same manner as in Example 1. The measurement results are shown in Table 1.

[0055] [Comparative Example 4] Except that an aluminum foil ("nippaku foil" manufactured by Mitsubishi Aluminum Corporation) with a thickness of 8.5 μm was used as the light-shielding substrate, and the thickness of the anti-gloss layer after drying was set to 2.25 μm, a light-shielding film was obtained in the same manner as in Example 1. The obtained light-shielding film was measured in the same manner as in Example 1. The measurement results are shown in Table 1.

[0056] [Comparative Example 5] The thickness of the substrate was set to 4.5 μm. The materials used to form the light-shielding layer were an amine ester adhesive resin ("Vylon40SS" manufactured by Toyobo Co., Ltd.) and a carbon black dispersion ("MHI BLACK#273" manufactured by Mikuni Pigment Co., Ltd.). The mass ratio of carbon black to the light-shielding layer was set to 12% by mass. The materials used to form the anti-gloss layer were a thermosetting adhesive resin ("KDC-03" manufactured by Kohshin Chemical Co., Ltd.), silicon dioxide particles ("Sylysia420" manufactured by Fujisilica Co., Ltd.), and a carbon black dispersion ("MHI BLACK#273" manufactured by Mikuni Pigment Co., Ltd.). The mass ratio of carbon black to the anti-gloss layer was set to 4% by mass. The thickness of the anti-gloss layer was set to 4.0 μm. Otherwise, a light-shielding film was obtained in the same manner as in Example 1. The obtained light-shielding film was measured using the above method. The measurement results are shown in Table 1. [Table 1] Table 1 Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Thickness (μm) of the light-shielding substrate 9 9 9 12 9 8.5 7.5 Thickness (μm) of the light-shielding film 16 16 16 twenty two 9 13 15.5 Black component content (by mass) of the anti-gloss layer 4 4 4 4 - 4 4 Gloss (%) 0.2 0.2 0.2 0.2 38.1 - 0.2 OD value 6.3 6.3 6.2 6.2 - - 6.1 Substrate with light-blocking properties Surface resistivity (Ω / □) 2.0×10 3 1.6×10 5 7.9×10 15 6.6×10 14 2.0×10 3 5.0×10 -3 >1.0×10 16 Surface resistivity of the light-shielding film (Ω / □) 2.9×10 3 1.8×10 4 1.4×10 15 4.1×10 5 2.0×10 3 8.6×10 5 4.1×10 5 In the table, the OD value represents the optical density value.

[0057] In Examples 1 and 2, the surface resistivity of the light-shielding film was 1.0 × 10⁵ Ω / □ or less. On the other hand, in Comparative Examples 1, 2, 4, and 5, the surface resistivity of the light-shielding film exceeded 1.0 × 10⁵, resulting in insufficient antistatic function and low workability. For example, in Comparative Example 3, when the light-shielding film did not have an anti-gloss layer, the 60-degree gloss level was very high, failing to achieve low reflectivity. [Industrial Applicability]

[0058] According to the present invention, a light-shielding film that combines low reflectivity and workability can be provided. Furthermore, the light-shielding film of the present invention can be used in a lens unit. [Simplified Explanation of the Diagram]

[0009] [Figure 1] is a cross-sectional view of a light-shielding film of one embodiment of the present invention. [Figure 2] is a cross-sectional view of a light-shielding film of one embodiment of the present invention. [Figure 3] is an exploded view of a lens unit of one embodiment of the present invention.

Claims

1. A light-shielding film comprising a light-shielding substrate and an anti-gloss layer superimposed on the substrate, wherein the anti-gloss layer is more transparent than the substrate, the light-shielding film has an optical density of 4.0 or more at a wavelength of 380 nm to 780 nm, at least one surface of the anti-gloss layer has a gloss of 0.0% to 10.0% at an incident angle of 60 degrees, the light-shielding film has a surface resistivity of 1.0 × 10⁵ Ω / □ or less, and the substrate has antistatic properties.

2. As in request item 1, the light-shielding film, wherein, The substrate contains carbon black.

3. As in request item 1, the light-shielding film, wherein, The anti-gloss layer contains carbon black, and the content of carbon black in the anti-gloss layer is greater than 0% by mass and less than 5% by mass.

4. As in request item 1, the light-shielding film, wherein, The anti-gloss layer contains adhesive resin and particles dispersed within the adhesive resin.

5. As in request item 1, the light-shielding film, wherein, The thickness of the light-shielding film is less than 35 μm.

6. As in request item 1, the light-shielding film, wherein, The thickness of the substrate is between 2 μm and 30 μm.

7. The light-shielding film as requested in item 1, wherein, The thickness of the anti-gloss layer is between 1 μm and 7 μm.

8. The light-shielding film of any of the claims 1 to 7 is disposed on the shutter, aperture component, or gap adjustment component between multiple lenses of an optical component.

9. A lens unit comprising the light-shielding film of claim 8.

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